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Unusually extensive networks of vocal recognition in African elephants
Abstract
Research on acoustic communication has often focused on signalling between territorial individuals or static neighbouring groups. Under these circumstances, receivers have the opportunity to learn to recognize the signals only of the limited number of conspecifics with which they are in auditory contact. In some mammals, however, social units move freely with respect to one another and range widely, providing individuals with opportunities to learn to recognize the signals of a wide range of conspecifics in addition to those of their immediate neighbours. We conducted playback experiments on African elephants,Loxodonta africana , in Amboseli National Park, Kenya, to determine the extent to which adult female elephants, which have a highly fluid social system, can recognize others in the population through infrasonic contact calls. Female elephants could distinguish the calls of female family and bond group members from those of females outside of these categories; moreover, they could also discriminate between the calls of family units further removed than bond group members, on the basis of how frequently they encountered them. We estimated that subjects would have to be familiar with the contact calls of a mean of 14 families in the population (containing around 100 adult females in total), in order to perform these discriminations. Female elephants thus appear to have unusually extensive networks of vocal recognition, which may prove to be typical of long-lived species that have both fluid social systems and the means for long-distance vocal communication.
... African elephants use a complex olfactory system to discriminate between scents to one changed molecule and have the largest repertoire of olfactory receptor genes reported so far [1][2][3]. This allows them to detect resources and find mating partners in the wild [4][5][6][7][8][9]. ...
... Olfaction is, next to vision, not only important for the recognition of relatives but also triggers the release of the hormone oxytocin, which stimulates the mother-child bond [13,14]. Elephant bonds are among the strongest in mammals, and especially the relationship between mothers and daughters is the longest, closest, and most intense of all known family bonds [2,11]. The capacity to recognize long-time absent and even mortal remains of relatives is hypothesized to be the result of their complex olfactory abilities [2,15,16]. ...
... Elephant bonds are among the strongest in mammals, and especially the relationship between mothers and daughters is the longest, closest, and most intense of all known family bonds [2,11]. The capacity to recognize long-time absent and even mortal remains of relatives is hypothesized to be the result of their complex olfactory abilities [2,15,16]. However, there are no empirical data giving evidence for an olfactory memory in African elephants longer than one year, neither under ex situ nor in situ conditions [3]. ...
Simple Summary
African elephants are known for their long memory; this is also valid for their olfactory sense and their ability to discriminate scents. This feature is highly important for these mammals to maintain their family bonds and to differentiate between familiar and unfamiliar individuals. Thus far, scientific data only testify to an olfactory memory of up to one year for African elephants. This study investigated the long-term olfactory memory of two mother-daughter pairs that were separated for 2 and 12 years, respectively. Results showed that all four elephants were able to recognize their separated relatives just by the scent of feces, thereby giving the empirical implication of olfactory memory in African elephants of up to 12 years.
Abstract
African elephants are capable of discriminating scents up to a single changed molecule and show the largest reported repertoire of olfactory receptor genes. Olfaction plays an important role in family bonding. However, to the best of our knowledge, no empirical data exist on their ability to remember familiar scents long-term. In an ethological experiment, two mother-daughter pairs were presented with feces of absent kin, absent non-kin, and present non-kin. Video recordings showed reactions of elephants recognizing kin after long-term separation but only minor reactions to non-kin. Results give the empirical implication that elephants have an olfactory memory longer than 1 year and up to 12 years and can distinguish between kin and non-kin just by scent. These findings confirm the significance of scent for family bonds in African elephants.
... When an elephant in a social group exhibits distress, others often vocalize toward the distressed individual as a signal that may function as reassurance (Moss, Croze, & Lee, 2011;. Affiliated social groups rely on vocalizations to find each other, and some groups may use these signals to avoid unfamiliar individuals (Fishlock & Lee, 2013;McComb, Moss, Sayialel, & Baker, 2000). After sexually mature male elephants disperse from family groups, their movement patterns, especially in relation to social contact, are often motivated by the presence of unrelated estrus females (Poole, 1987). ...
... Elephants have also been tested on more fine-scale, ecologically valid discriminations. African savanna elephants are able to discriminate contact calls from an average of 14 families, which include vocalizations of 100 individuals (McComb et al., 2000). Discriminations of familiar versus unfamiliar infrasonic (Stoeger & Baotic, 2017) and seismic calls by males and females have also been demonstrated in wild African savanna elephants. ...
... Rensch also described melody recognition in this elephant even when the melody's frequency, intensity, rhythm, and timbre were changed. In some of the aforementioned studies of individual recognition of communication signals in African savanna elephants, the research addressed not only auditory perception but also aspects of elephant cognition such as categorization and memory (McComb et al., 2000(McComb et al., , 2003. For example, McComb et al. (2014) found that savanna elephants behaved differently based on the perceived threat associated with the acoustic signals of particular categories of humans. ...
... Elephants hold significant intrinsic, biological, ecological and human cultural value. They possess unique genetic and physiological features [1], exhibit high levels of individual cognitive and emotional intelligence [2][3][4], maintain complex social behaviours and structures [5][6][7][8][9], serve as keystone species in their respective ecosystems [10][11][12], are highly valued by their local communities [13] and serve as flagship species for animal conservation [14]. ...
... There is strong evidence that elephants can identify other individuals from their calls [5,6], and researchers have also had some success in individual classification from audio data as well. Clemins et al. [144] demonstrated 83% accuracy in identifying individuals by employing a hidden Markov model with feature extraction. ...
Artificial intelligence (AI) and machine learning (ML) present revolutionary opportunities to enhance our understanding of animal behaviour and conservation strategies. Using elephants, a crucial species in Africa and Asia’s protected areas, as our focal point, we delve into the role of AI and ML in their conservation. Given the increasing amounts of data gathered from a variety of sensors like cameras, microphones, geophones, drones and satellites, the challenge lies in managing and interpreting this vast data. New AI and ML techniques offer solutions to streamline this process, helping us extract vital information that might otherwise be overlooked. This paper focuses on the different AI-driven monitoring methods and their potential for improving elephant conservation. Collaborative efforts between AI experts and ecological researchers are essential in leveraging these innovative technologies for enhanced wildlife conservation, setting a precedent for numerous other species.
... Both sexes approached the loudspeaker in response to Pant calls; territorial males also responded with dung or urine marking, showing the possibility to stimulate territorial behavior with playbacks (Cinkov a & Shrader, 2020). Wild anoestrous females reacted more intensively to Pants of unfamiliar senders than to controls (Cinkov a & Shrader, 2022), so the familiarity may affect responses, as shown in elephants (McComb et al., 2000). ...
... However, automated systems are static and triggered by movement, so would need to be placed along known dispersal paths or at very high densities; such limitations mean that successful deployment may only be possible in small reserves. Familiar Pant calls would be the optimal stimulus since both sexes responded by approaching the speaker, and familiar calls are less likely to cause aggression and stress (Herbinger et al., 2009;McComb et al., 2000). Alternatively, the system could be combined with an identification software based around artificial intelligence to adapt the playback to the target individual. ...
Translocations can be a useful management tool to support endangered species. Translocated white rhinoceroses sometimes disperse from their release sites and leave protected areas, requiring sedation and return transport by vehicles. To avoid stressful transportation, less invasive management tools are needed to get animals back to the release site. We tested whether playbacks of white rhinoceros calls can influence their movements and thereby offer a potential management tool. We performed 200 experiments with 26 free‐roaming white rhinoceroses in two reserves in Botswana and recorded response intensity and duration, including body movement toward and away from the loudspeaker in response to a socio‐positive and a socio‐negative call. Rhinoceroses responded more to conspecific calls than to control sounds but did not show consistent behavioral responses across all experiments per call type. Males approached the loudspeaker more often than females. The intensity of responses was higher for calls recorded from unfamiliar than from familiar callers and behavioral responses differed between reserves. Further research is necessary to develop an applicable design for a combination of playbacks that would more reliably lead to directed body movement responses.
... Examples are receiving preferred food or social attention as well as access to preferred social or mating partners and mating itself. Animals often produce specific signals in such contexts (McComb et al., 2000;Pradhan et al., 2006;Slocombe & Zuberbuehler, 2006;Serrapica et al., 2017) and studying these can lead to indicators of joy. ...
... (c) Acoustic signals in positive contexts Acoustic communication is widespread in birds and mammals, and may be the most common form of communication in these taxa (e.g. McComb et al., 2000;Pradhan et al., 2006;Slocombe & Zuberbuehler, 2006;Wilson et al., 2008). Therefore, if non-human joy or other measures of event-driven positive affect are communicated to others, vocalisations emitted exclusively during pleasurable experiences would be a clear path to investigate. ...
The nature and evolution of positive emotion is a major question remaining unanswered in science and philosophy. The study of feelings and emotions in humans and animals is dominated by discussion of affective states that have negative valence. Given the clinical and social significance of negative affect, such as depression, it is unsurprising that these emotions have received more attention from scientists. Compared to negative emotions, such as fear that leads to fleeing or avoidance, positive emotions are less likely to result in specific, identifiable, behaviours being expressed by an animal. This makes it particularly challenging to quantify and study positive affect. However, bursts of intense positive emotion (joy) are more likely to be accompanied by externally visible markers, like vocalisations or movement patterns, which make it more amenable to scientific study and more resilient to concerns about anthropomorphism. We define joy as intense, brief, and event-driven (i.e. a response to something), which permits investigation into how animals react to a variety of situations that would provoke joy in humans. This means that behavioural correlates of joy are measurable, either through newly discovered 'laughter' vocalisations, increases in play behaviour, or reactions to cognitive bias tests that can be used across species. There are a range of potential situations that cause joy in humans that have not been studied in other animals, such as whether animals feel joy on sunny days, when they accomplish a difficult feat, or when they are reunited with a familiar companion after a prolonged absence. Observations of species-specific calls and play behaviour can be combined with biometric markers and reactions to ambiguous stimuli in order to enable comparisons of affect between phylogenetically distant taxonomic groups. Identifying positive affect is also important for animal welfare because knowledge of positive emotional states would allow us to monitor animal well-being better. Additionally, measuring if phylogenetically and ecologically distant animals play more, laugh more, or act more optimistically after certain kinds of experiences will also provide insight into the mechanisms underlying the evolution of joy and other positive emotions, and potentially even into the evolution of consciousness.
... Arguably, if slime mold in a petri dish is at one end of a scale of organismal movement complexity, the other terrestrial extreme could be represented by forest elephant movements in a tropical rainforest. Elephants are the largest and among the most long-lived, intelligent, and socially complex terrestrial animals (Filippi et al., 2017;Healy et al., 2014;McComb et al., 2000;Wittemyer et al., 2005;, and tropical rainforests are the most diverse ecosystems on the planet (Connell, 1978). As keystone species and ecosystem engineers (Berzaghi et al., 2019;Blake et al., 2009), patterns of forest elephant movements may have profound impacts on the structure and composition of their habitats, which feeds back into shaping future elephant movement trajectories in an oscillating cycle (Blake et al., 2009). ...
... Forest elephant core social units are small, usually consisting of one or two adult females and their dependent offspring (Merz, 1986;Turkalo & Barnes, 2013;White et al., 1993); however, their larger-scale social organization is more complex (Goldenberg et al., 2021) involving consistent associations among core units. Unlike savannah elephants in which extended matriarchal hierarchies are the norm (McComb et al., 2000;Wittemyer et al., 2005), small core group size in forest elephants is likely driven by a combination of intraspecific competition for patchy food Fig. 3.3 A bull named Sue was fitted with a GPS collar at Mabalé Bai, in the Nouabalé-Ndoki National Park, Republic of Congo (a). Sue visited the bai primarily at night to drink mineral-rich water and move out into the surrounding forest during the day to forage (b). ...
To survive, all organisms must maximize energy input and reproductive output and minimize risk. This applies to how they travel through their environment. Due to numerous mechanical and physical laws that scale allometrically, forest elephants (Loxodonta cyclotis), as the largest vertebrate inhabitants of Africa’s dense tropical forests, solve this optimization in rather different ways than the smallest, for example, shrews. In this chapter, we discuss how body size influences animal ranging and why elephants ought to have very large ranges. We then use GPS telemetry data we collected ourselves and additional data from published studies to characterize home range size and other movement metrics of forest elephants in Central Africa. We demonstrate how the availability of water, food, nutrients, social organization, sex, and personality combines to drive the movements of forest elephants. We conclude that these factors are largely trumped by a human-induced landscape of fear throughout the range of forest elephants. We explain how the combination of large body size and the extent of forest elephant movements lead to their profound ecosystem engineering impacts, which help maintain forest biodiversity and increase carbon sequestration. We then show how human activities, primarily poaching and infrastructure development, restrict elephant movements, with negative consequences for forest function that have globally relevant ramifications. We finally argue that if forest elephant movements in their present form are to be maintained, the planet’s rich nations must match and surpass the impressive legislation for protected areas made by forest elephant range states in their commitment to demand and create the economic conditions needed for the sustainable management of tropical forest resources, including elephants.KeywordsAnimal movementTropical forestCongo BasinConservationEcosystem engineerHome range
... Evidence of a mulƟ-modal use of socially directed calls (124). Bonobos' calls show complex paƩerns of signaling to convey different social goals of sex (125), and their vocalizaƟons seem structurally more complex than those of chimpanzees (126) Polymodal (acousƟc, visual, tacƟle, chemical) and variable communicaƟon, with extensive informaƟon sharing (127)(128)(129)(130)(131)(132)(133)(134)(135)(136)(137)(138) Play Young children spend a large proporƟon of their Ɵme playing (9 to 58%), depending on culture, gender, and age (139,140). Advanced pretend play parallels language development (141,142); social and pretend play in hunter-gatherers are used to counteract dominance tendencies (143) During juvenile period, play-fighƟng becomes longer and more cooperaƟve (144). ...
... For example, elephants in Kenya have different alarm calls for humans and for bees, which elicit different responses (134,136). Research has shown that African elephants can recognize a large network of individuals by contact vocalizations alone (130). All three species also produce calls combining several types of vocalizations in different orders, indicating potential syntax in these combination calls (179). ...
Humans are unique in their sophisticated culture and societal structures, their complex languages, and their extensive tool use. According to the human self-domestication hypothesis, this unique set of traits may be the result of an evolutionary process of self-induced domestication, in which humans evolved to be less aggressive and more cooperative. However, the only other species that has been argued to be self-domesticated besides humans so far is bonobos, resulting in a narrow scope for investigating this theory limited to the primate order. Here, we propose an animal model for studying self-domestication: the elephant. First, we support our hypothesis with an extensive cross-species comparison, which suggests that elephants indeed exhibit many of the features associated with self-domestication (e.g., reduced aggression, increased prosociality, extended juvenile period, increased playfulness, socially regulated cortisol levels, and complex vocal behavior). Next, we present genetic evidence to reinforce our proposal, showing that genes positively selected in elephants are enriched in pathways associated with domestication traits and include several candidate genes previously associated with domestication. We also discuss several explanations for what may have triggered a self-domestication process in the elephant lineage. Our findings support the idea that elephants, like humans and bonobos, may be self-domesticated. Since the most recent common ancestor of humans and elephants is likely the most recent common ancestor of all placental mammals, our findings have important implications for convergent evolution beyond the primate taxa, and constitute an important advance toward understanding how and why self-domestication shaped humans' unique cultural niche.
... To that end, I presented myself to each elephant through a variety of sensory pathways as I attempted to continually renegotiate consent to my presence. For example, elephants have impressive hearing and auditory recall, recognizing the individual voices of conspecifics over a kilometer away; they can also vary their responses in answer to the unique questions or statements received from others (McComb, et al. 2000). Some elephants (albeit wild African elephants [Loxodonta Africana]) have demonstrated the capacity to identify ethnicity, age, and gender from human voices (McComb, et al. 2014). ...
... And artists have acknowledge that animal cruelty is no longer accepted without criticism in the context of works of art and that criticism can come from within their own community and not only from 'philistines' without any deeper understanding of contemporary art -which was for a long time the argument when the general public disapproved of animal abuse in artworks, for example the notorious animal killings in the performance art of the 1970s (Ullrich 2014b). Also, in the last couple of years art historians or art critics increasingly consider ethical implications of the inclusion of living non-human animals or the sourcing of dead nonhuman animals in artmaking practices or art exhibitions when discussing artworks (Aloi 2011;Baker 2000Baker , 2013Watt 2012;Burt 2009;Desmond 2012;Ullrich 2014aUllrich , 2015Ullrich , 2019. One of the latest examples is the article "Artistic Freedom or Animal Cruelty? ...
Lynn et al., (2019) accused fellow scientists of misrepresenting free-roaming cats
(Felis catus) by framing them as a global threat to biodiversity, rather than a
localised threat to specific ecosystems. These authors asserted that the narrative
created a ‘moral panic’ over free-roaming cats, which is escalated by emotive
journalistic pieces read by audiences around the world. To test this empirically, I
performed a thematic discourse analysis of user comments responding to five
news articles, a magazine, and a YouTube video related to the topic of freeroaming cats. The discourses examined flow between conservationists, the media,
and the public, and reflect the confused and convoluted ways in which people think
about cats. Here I discuss how well the data fits the moral panic theory. I analyse
how labels such as ‘feral’ serve to ‘other’ cats, rendering them objects of distain
and creating ‘folk devils’ that are deemed more killable than beloved companion
animals of the same species.
... Females and males are sexually dimorphic in size (e.g., males are taller and bulkier). The females maintain extensive networks of social relationships between related matrilines (McComb et al., 2000). These matriarchal family herds live in dynamic fission-fusion societies (Moss & Poole, 1983;Vidya & Sukumar, 2005), which are characterized by temporary merging of and splitting into family units that consist of groups of approximately 20 individuals (L. ...
... Rumble vocalizations are uttered in multiple contexts, which include short-and long-distance communication. They range from coordinating movement and group activities, maintaining family group cohesion, keeping vocal contact with affiliates, and prompting defensive and exploratory behavior (Leighty et al., 2008;McComb et al., 2000McComb et al., , 2003Poole, 2011). ...
Vocal production learning is the ability to modify a vocal output in response to auditory experience. It is essential for human speech production and language acquisition. Vocal learning evolved independently several times in vertebrates, indicating evolutionary pressure in favor of this trait. This enables cross-species comparative analysis to be used to test evolutionary hypotheses. Humans share this ability with a versatile but limited group of species: songbirds, parrots and hummingbirds, bats, cetaceans, seals, and elephants. Although case studies demonstrate that African savanna and Asian elephants are capable of heterospecific imitation, including imitation of human words, our understanding of both the underlying mechanisms and the adaptive relevance within the elephant’s natural communication system is limited. Even though comparing phylogenetically distant species is intriguing, it is also worthwhile to investigate whether and to what extent learned vocal behavior is apparent in species phylogenetically close to an established vocal learner. For elephants, this entails determining whether their living relatives share their special ability for (complex) vocal learning.
In this review, we address vocal learning in Elephantidea and Sirenia, sister groups within the Paenungulata. So far, no research has been done on vocal learning in Sirenians. Because of their aquatic lifestyle, vocalization structure, and evolutionary relationship to elephants, we believe Sirenians are a particularly interesting group to study. This review covers the most important acoustic aspects related to vocal learning in elephants, manatees, and dugongs, as well as knowledge gaps that must be filled for one to fully comprehend why vocal learning evolved (or did not) in these distinctive but phylogenetically related taxa.
... These animals are able to discriminate familiar and unfamiliar calls, the former being used for maintaining contact and coordinating with members of a same group across long distances. For example, there is evidence that calls from family members are significantly responded to and followed by approaches to the area from which the call had originated (43). The author demonstrated that vocalisation brings information about presence and identity of callers and that this is shared for bonding and reunification purposes. ...
... The author demonstrated that vocalisation brings information about presence and identity of callers and that this is shared for bonding and reunification purposes. However, although familiar calls are addressed at one's group members, the loud nature of long-distance vocalisations and the propagation medium makes this type of communication prone to interception by listeners and does not allow the caller to stop unwanted listeners from eavesdropping (43). Although from our analysis we did not find studies on "secretive" communication in elephants, this cannot be excluded if we consider what happens in other species. ...
Privacy is an essential consideration when designing interactive systems for humans. However, at a time when interactive technologies are increasingly targeted at non-human animals and deployed within multispecies contexts, the question arises as to whether we should extend privacy considerations to other animals. To address this question, we revisited early scholarly work on privacy, which examines privacy dynamics in non-human animals (henceforth “animals”). Then, we analysed animal behaviour literature describing privacy-related behaviours in different species. We found that animals use a variety of separation and information management mechanisms, whose function is to secure their own and their assets' safety, as well as negotiate social interactions. In light of our findings, we question tacit assumptions and ordinary practises that involve human technology and that affect animal privacy. Finally, we draw implications for the design of interactive systems informed by animals' privacy requirements and, more broadly, for the development of privacy-aware multispecies interaction design.
... Among the calls for which we had recordings of the receiver and recordings of the caller addressing other individuals (n = 236), 59.7% were divergent from the receiver's calls; that is, less similar to the Elephants are among the few mammals capable of mimicking novel sounds, although the function of this vocal learning ability is unknown 10,11 . The most common elephant call type is the rumble, a harmonically rich, low-frequency sound that is individually distinct 12,13 and distinguishable 14 and is produced across most behavioural contexts 15 . Contact rumbles are long-distance calls produced when the caller is out of sight and more than ~50 m from one or more social affiliates and attempting to reinitiate contact. ...
Personal names are a universal feature of human language, yet few analogues exist in other species. While dolphins and parrots address conspecifics by imitating the calls of the addressee, human names are not imitations of the sounds typically made by the named individual. Labelling objects or individuals without relying on imitation of the sounds made by the referent radically expands the expressive power of language. Thus, if non-imitative name analogues were found in other species, this could have important implications for our understanding of language evolution. Here we present evidence that wild African elephants address one another with individually specific calls, probably without relying on imitation of the receiver. We used machine learning to demonstrate that the receiver of a call could be predicted from the call’s acoustic structure, regardless of how similar the call was to the receiver’s vocalizations. Moreover, elephants differentially responded to playbacks of calls originally addressed to them relative to calls addressed to a different individual. Our findings offer evidence for individual addressing of conspecifics in elephants. They further suggest that, unlike other non-human animals, elephants probably do not rely on imitation of the receiver’s calls to address one another.
... Solving the putatively more complex task encountered by litter-rearing mothers may not have required the evolution of new abilities, but rather have relied on the extension of existing auditory and cognitive skills to larger sets of offspring. Indeed, the "multilevel" communication system identified here bears similarities to those described in species living in social groups with different matrilines, such as elephants (Loxodonta africana) (45) or rhesus macaques (Macaca mulatta) (46), where animals are able to discriminate individuals among multiple conspecifics by using both group-and individual-related information. Whether mothers actually recognize individual puppies within their litter will have to be systematically tested in future experiments using, for example, a cross-modal expectancy violation paradigm (47) that could combine auditory cues (this study) with visual and/ or olfactory cues to identity (48). ...
In mammals, offspring vocalizations typically encode information about identity and body condition, allowing parents to limit alloparenting and adjust care. But how do these vocalizations mediate parental behavior in species faced with the problem of rearing not one, but multiple offspring, such as domestic dogs? Comprehensive acoustic analyses of 4,400 whines recorded from 220 Beagle puppies in 40 litters revealed litter and individual (within litter) differences in call acoustic structure. By then playing resynthesized whines to mothers, we showed that they provided more care to their litters, and were more likely to carry the emitting loudspeaker to the nest, in response to whine variants derived from their own puppies than from strangers. Importantly, care provisioning was attenuated by experimentally moving the fundamental frequency ( f o , perceived as pitch) of their own puppies’ whines outside their litter-specific range. Within most litters, we found a negative relationship between puppies’ whine f o and body weight. Consistent with this, playbacks showed that maternal care was stronger in response to high-pitched whine variants simulating relatively small offspring within their own litter’s range compared to lower-pitched variants simulating larger offspring. We thus show that maternal care in a litter-rearing species relies on a dual assessment of offspring identity and condition, largely based on level-specific inter- and intra-litter variation in offspring call f o . This dual encoding system highlights how, even in a long-domesticated species, vocalizations reflect selective pressures to meet species-specific needs. Comparative work should now investigate whether similar communication systems have convergently evolved in other litter-rearing species.
... Elephants exhibit one of the most complex social systems among mammal species centered around family groups consisting of related adult females and their offspring [19,20] with vocal communication playing a critical role in maintaining long-lasting social bonds between females [21][22][23]. All elephant species (African forest elephants Loxodonta cyclotis, African savanna elephants Loxodonta africana, and the Asian elephant Elephas maximus) frequently combine characteristic tonal low-frequency rumble vocalizations with noisy broadband calls (mainly roars, but also barks and cries) [24][25][26]. ...
Syntax, the combination of meaning-devoid phonemes into meaningful words, which in turn are combined in structurally and semantically complex sentences, is fundamental to the unlimited expressiveness of human languages. Studying the functions of call combinations in non-human species provides insights into the evolution of such syntactic capabilities. Here, we investigated the combination of high amplitude broadband calls with low frequency rumble vocalizations in a highly social species, the African forest elephant Loxodonta cyclotis . Rumbles play an integral role in coordinating social interactions by transmitting socially relevant information, including individual identity. By contrast, broadband calls, such as roars, are thought to function as signals of distress and urgency as they are typically produced in situations of high emotional intensity. Functional changes associated with the combination of these calls remain little understood. We found that call combinations were produced by all age-sex classes but were most prevalent in immature individuals. We found that rumbles used singularly occurred in all five investigated social contexts, whereas single broadband calls were restricted to two resource-related contexts. Call combinations also occurred in all five contexts, suggesting an increase in the functional use of broadband calls when combined with rumbles, analogous to the generativity brought about through syntax in human speech. Moreover, combining calls appeared to lead to functional shifts towards high-stake contexts. Call combinations were more likely in competition contexts compared to single rumbles, and more likely in separation contexts compared to single broadband calls. We suggest that call combination in forest elephants may aide to reduce message ambiguity in high-stake situation by simultaneously communicating distress and individual identity, which may be critical to secure access to resources, reduce the risk of injury and to reunite with or recruit the support of the family group.
... long-term social memory | social relationships | eye-tracking | primates | cognitive evolution Complex sociality requires individuals to recognize and remember conspecifics across space and time (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13). Long-term memory for social partners and interactions allows animals to build individual relationships, strategically navigate dominance hierarchies and alliances, and avoid hostile interactions (1,2,14). ...
Recognition and memory of familiar conspecifics provides the foundation for complex sociality and is vital to navigating an unpredictable social world [Tibbetts and Dale, Trends Ecol. Evol. 22 , 529–537 (2007)]. Human social memory incorporates content about interactions and relationships and can last for decades [Sherry and Schacter, Psychol. Rev. 94 , 439–454 (1987)]. Long-term social memory likely played a key role throughout human evolution, as our ancestors increasingly built relationships that operated across distant space and time [Malone et al ., Int. J. Primatol. 33 , 1251–1277 (2012)]. Although individual recognition is widespread among animals and sometimes lasts for years, little is known about social memory in nonhuman apes and the shared evolutionary foundations of human social memory. In a preferential-looking eye-tracking task, we presented chimpanzees and bonobos ( N = 26) with side-by-side images of a previous groupmate and a conspecific stranger of the same sex. Apes’ attention was biased toward former groupmates, indicating long-term memory for past social partners. The strength of biases toward former groupmates was not impacted by the duration apart, and our results suggest that recognition may persist for at least 26 y beyond separation. We also found significant but weak evidence that, like humans, apes may remember the quality or content of these past relationships: apes’ looking biases were stronger for individuals with whom they had more positive histories of social interaction. Long-lasting social memory likely provided key foundations for the evolution of human culture and sociality as they extended across time, space, and group boundaries.
... Asian elephants exist in a basic unit, comprising of mother and dependent-offspring (Mckay, 1973;Sukumar, 1989). In southeastern Sri Lanka and southern India, 'joint family groups' of Asian elephants is noticed where two or more mothers are the family head and the oldest one is considered as the repository of critical ecological information (McComb et al., 2000(McComb et al., , 2001. She guides movement pattern and habitat utilization by the family group. ...
Diurnal activity pattern and time budgeting of female Asian elephant (Elephas maximus) was studied at Alipore Zoological Garden, Kolkata, India, for seven hours observation period from 10.00 to 17.00 h between August, 2022 to June, 2023 by using focal sampling method with 23,520 minutes of observations. The study identified 14 different high frequency behaviour and 16 low frequency behaviour of the elephant during the observation. The elephant exhibited significant variations in activities among the seasons and in the different hours within a day. For all the studied seasons, foraging activity was dominant with significantly (P<0.05) maximum time spent, followed by ear flapping (9.91±.09%), standing (9.52±0.69%) and walking (8.76±0.10%) during monsoon, walking (11.14±0.62%), ear flapping (9.33±0.33%) and standing (7.85±0.52%) during winter and, standing (11.95±0.37%), ear flapping (11.14±0.31%) and dusting (10.29±0.45%) during summer. Among seasons, significantly higher (P<0.05) mean time spent percentage was noted in playing and mudding activities during monsoon, in foraging, walking and stereotypic behaviour, bobbing during winter and in standing and dusting during summer. Similarly, significantly lowest (P<0.05) time spent was observed, during monsoon for dusting activity, during summer for foraging, playing, walking, mudding and bobbing activities and during winter for standing, ear flapping and bathing. In hourly activity time budget, the peak hour of foraging was 15.00-16.00 h for all the studied seasons. The findings of the present observational study on activity time budget of a captive Asian elephant would be helpful for comparing the behavioural patterns of captive and wild elephant which would be ultimately useful in improving the management strategies for the welfare of captive Asian elephants.
... This includes factors of interpersonal dynamics, rapport, and contextual sound significance. Infamous examples include the 2000 experiment that subjected a family of African Savannah elephants (Loxodonta africana) to the playback vocalization of one of their deceased kin, leading them to a state of grief (McComb et al., 2000). Another ethicallyquestionable example is the anecdotal use of conspecific recordings when handfeeding chicks in major avian preservation centers. ...
There is a strong disconnect between humans and other species in our societies. Zoos particularly expose this disconnect by displaying the asymmetry between visitors in search of entertainment, and animals often suffering from a lack of meaningful interactions and natural behaviors. In zoos, many species are unable to mate, raise young, or exhibit engagement behaviors. Enrichment is a way to enhance their quality of life, enabling them to express natural behaviors and reducing stereotypies. Prior work on sound-based enrichment and interactivity suggest that a better understanding of animals’ sensory needs and giving them options to shape their surroundings can yield substantial benefits. However, current zoo management and conservation practices lack tools and frameworks to leverage innovative technology to improve animal well-being and zookeepers’ ability to care for them. Ethical considerations are called for in developing such interventions as human understanding of animals’ worlds is still limited, and assumptions can have detrimental consequences. Based on several interventions, four principles are proposed to guide a more systematic implementation of sonic enrichment in zoos. The goal is to lay the groundwork for the design of the zoos of the future, with a focus on sounds, for the benefit of the animals.
... By some ACI scholars' reasoning, playing back animals' vocalisations is unwise on account of humans poor awareness of what those vocalisations mean to the animals [46]. Also, such playback arguably holds potential to cause stress to the animals not least because they hear these sounds without other animals being present [30]. We accounted for this factor by creating an element of choice in both settings: an animal not wishing to hear the audio could elect not to trigger the device, by avoiding activation of the system. ...
Though computer systems have entered widespread use for animals' enrichment in zoos, no interactive computer systems suited to giraffes have yet been developed. Hence, which input modes or audio stimuli giraffes might best utilise remains unknown. To address this issue and probe development of such systems alongside the animals themselves and zookeepers, researchers gathered requirements from the keepers and from prototyping with giraffes, then created two interfaces -- one touch-based and one proximity-based -- that play giraffe-humming audio or white noise when activated. Over two months of observation, giraffes utilised the proximity-based system more frequently than the touch-based one but in shorter episodes. Secondly, the study highlighted the significance of considering user-specific needs in computer systems' development: the lack of preference shown for any specific audio type indicates that the audio stimuli chosen were inappropriate for these giraffes. In addition, the paper articulates several lessons that can be drawn from human--computer interaction when one develops systems for animals and, in turn, what the findings presented mean for humans.
... ruminants: [5,6]; felids: [7]; rodents: [8]), updating vocal individuality of social partners can be necessary over time. Individual vocal recognition is also important for developing and mediating social relationships [9][10][11]. For example, human listeners can recognize familiar individuals by processing the spectral features of their voices [12,13]. ...
Variation in formant frequencies has been shown to affect social interactions and sexual competition in a range of avian species. Yet, the anatomical bases of this variation are poorly understood. Here, we investigated the morphological correlates of formants production in the vocal apparatus of African penguins. We modelled the geometry of the supra-syringeal vocal tract of 20 specimens to generate a population of virtual vocal tracts with varying dimensions. We then estimated the acoustic response of these virtual vocal tracts and extracted the centre frequency of the first four predicted formants. We demonstrate that: (i) variation in length and cross-sectional area of vocal tracts strongly affects the formant pattern, (ii) the tracheal region determines most of this variation, and (iii) the skeletal size of penguins does not correlate with the trachea length and consequently has relatively little effect on formants. We conclude that in African penguins, while the variation in vocal tract geometry generates variation in resonant frequencies supporting the discrimination of conspecifics, such variation does not provide information on the emitter's body size. Overall, our findings advance our understanding of the role of formant frequencies in bird vocal communication.
... According to the social intelligence hypothesis, we may thus expect them to build up social knowledge about group members, which is in line with the results from our playback experiments under captive and field conditions. Memorizing individuals and their relationships over years fits well to what is known from other social animals (review on individual recognition: Yorzinski 2017; social memory: e.g., McComb et al. 2000;Bruck 2013). Possibly, longterm memory for group members is the rule rather than an exception in species living in structured social groups. ...
Ravens and other corvids are renowned for their ‘intelligence’. For long, this reputation has been based primarily on anecdotes but in the last decades experimental evidence for impressive cognitive skills has accumulated within and across species. While we begin to understand the building blocks of corvid cognition, the question remains why these birds have evolved such skills. Focusing on Northern Ravens Corvus corax , I here try to tackle this question by relating current hypotheses on brain evolution to recent empirical data on challenges faced in the birds’ daily life. Results show that foraging ravens meet several assumptions for applying social intelligence: (1) they meet repeatedly at foraging sites, albeit individuals have different site preferences and vary in grouping dynamics; (1) foraging groups are structured by dominance rank hierarchies and social bonds; (3) individual ravens memorize former group members and their relationship valence over years, deduce third-party relationships and use their social knowledge in daily life by supporting others in conflicts and intervening in others’ affiliations. Hence, ravens’ socio-cognitive skills may be strongly shaped by the ‘complex’ social environment experienced as non-breeders.
... The larger the repertoire of elements, the greater the combinatorial diversity of sequences, and the more complex the information content of signals (Backhouse et al., 2022;Balsby et al., 2017;Clay and Zuberbühler, 2011;Dalziell and Welbergen, 2016;Leroux et al., 2021;Mitoyen et al., 2019;Scholes, 2008). In addition to behavioral state, groupliving animals may use complex signals to communicate group or individual identity (Mammen and Nowicki, 1981;McComb et al., 2000;McCowan and Hooper, 2002). The dialects of passerine songbirds represent one such form of variation, with individuals exhibiting discrimination between familiar and unfamiliar dialects (Briefer et al., 2013;Farabaugh et al., 1988;Henry et al., 2015;Marler and Slabbekoorn, 2004;Marler and Tamura, 1962;Searcy et al., 1981). ...
Dialectic signatures in animal acoustic signals are key in identification and association with group members. Complex vocal sequences may also convey information about behavioral state, and may thus vary according to social environment. Some bird species such as psittaciforms learn and modify their complex acoustic signals throughout their lives. However, the structure and function of vocal sequences in open-ended vocal learners remains understudied. Here, we examined vocal sequence variation in the warble song of budgerigars, and how these change upon contact between social groups. Budgerigars are open-ended vocal learners which exhibit fission-fusion flock dynamics in the wild. We found that two captive colonies of budgerigars exhibited colony-specific differences in the syntactic structure of their vocal sequences. Individuals from the two colonies differed in the propensity to repeat certain note types, forming repetitive motifs which served as higher-order signatures of colony identity. When the two groups were brought into contact, their vocal sequences converged, and these colony-specific repetitive patterns disappeared, with males from both erstwhile colonies now producing similar sequences with similar syntactic structure. We present data suggesting that the higher-order temporal arrangement of notes/vocal units is modified throughout life by social learning as groups of birds continually associate and dissociate. Our study sheds light on the importance of examining signal structure at multiple levels of organisation, and the potential for psittaciform birds as model systems to examine the influence of learning and social environment on acoustic signals.
... These calls reflect group membership, lineage, or social affiliation (e.g., [103,104]). Bloomfield et al. [86] suggest that the discrimination of individuals is through a 'constellation of features' of calls, with individuality in calling recognized for many mammal species [105][106][107][108][109], including bats (e.g., [102,110,111]); primates (e.g., [112][113][114][115][116][117][118]); rodents (e.g., [119,120]); carnivores (e.g., [121][122][123][124][125][126][127][128]); proboscideans (e.g., [129]); perissodactyls (e.g., [130][131][132]); artiodactyls (e.g., [133][134][135]); and pinnipeds (e.g., [136]). Sixty years of research have been dedicated to describing signature whistles in dolphin species [137]. ...
The behavioural, physiological, and energetic repercussions for wildlife that result from changes in their soundscapes are increasingly being realized. To understand the effects of changing acoustic landscapes, we first must establish the importance of the acoustic sense for species to transfer information between the environment, con- and heterospecifics, and a receiver, and the functional role of calling in behaviours such as foraging, navigation, mate attraction, and weaning. This review begins with a discussion of the use of calling and the acquisition of the vocal repertoire, before providing examples from multiple taxa on the functional applications of signals and communication. The acoustic sensory mode adds to, if not being inherent in, many critical life history stages over a range of species. The potential effects on an animal resulting from a change in its perceived soundscape and disturbance on its acoustics use is outlined. This can then be used to consider the implications of an altered acoustic niche or active space in the success and survival of an individual or species. Furthermore, we discuss briefly metrics that could be used to understand the implications of these changes, or could be used to guide mitigation action to lessen the impact.
... Not only is there strong evidence that elephants can identify other individuals from their calls [77,78], researchers have also had some success in individual classification from audio data as well. Clemins et al. [79] demonstrated 83% accuracy in identifying individuals by employing a hidden Markov model with feature extraction. ...
Artificial intelligence (AI) and machine learning (ML) present revolutionary opportunities to enhance our understanding of animal behavior and conservation strategies. Using elephants, a crucial species in Africa's protected areas, as our focal point, we delve into the role of AI and ML in their conservation. Given the increasing amounts of data gathered from a variety of sensors like cameras, microphones, geophones, drones, and satellites, the challenge lies in managing and interpreting this vast data. New AI and ML techniques offer solutions to streamline this process, helping us extract vital information that might otherwise be overlooked. This paper focuses on the different AI-driven monitoring methods and their potential for improving elephant conservation. Collaborative efforts between AI experts and ecological researchers are essential in leveraging these innovative technologies for enhanced wildlife conservation, setting a precedent for numerous other species.
... Their cognitive skills make elephants potential model organisms to increase our understanding of people (Bradshaw & Schore, 2007;Hawley, 2011). African savanna elephants: African savanna elephants are able to recognize up to 30 relatives from cues in urine and are aware of the location of these elephants (Bates et al., 2008), and are able to distinguish between the contact calls of elephants in their family and bonded group from elephants outside these group, indicating they are familiar with the acoustic communication of about 100 adult cows (McComb et al., 2000). African forest elephant: Forest elephants have different personalities and express remarkable variation in movement patterns . ...
Biodiversity conservation strategies may prioritise certain values of nature over others. Whilst there will likely always be a need for compromise in conservation planning, the consequences of trade-offs depend on peoples' relative perceptions of values that are promoted or neglected. In practice, not fully understanding or taking into account the value systems of all stakeholders, including local people, leads to contention, social inequality, and ineffectiveness. Elephants provide an excellent case study to illustrate the need for multidimensional valuation systems as they provide multiple overlapping services and benefits in ecological, socio-cultural, economic, and spiritual dimensions. Yet, their conservation is often highly contentious and fiercely debated. Here, we present a pluralist valuation system that identifies the varied services and benefits of elephants, but which adds important dimensions missing from current frameworks such as that of IPBES. Two key additions: (1) incorporating moral values alongside the services and benefits, and (2) incorporating a feedback loop to promote mutually reinforcing interactions, will better support holistic and equitable conservation. Additionally, to aid the interrogation of the kinds of problems that lead to contention in elephant conservation, we mapped the types of trade-offs that occur when different values are at stake, which allows us to identify balanced conservation solutions that will lead to unity. This pluralist valuation approach, which is similarly applicable to other species and ecosystems, clarifies the necessity of properly accounting for stakeholder values in decision making, and promotes fairer conservation decisions that will generate broader buy-in and support, uniting people, and facilitating socially just and sustainable conservation outcomes.
... Separations are driven by seasonal resource competition, and fusions allow elephants to maintain relationships of different types that may be beneficial (Douglas-Hamilton 1972;Moss 1988;Wittemyer et al. 2005). One such social benefit that may be exceptionally important for translocated elephants learning a new environment is information exchange (McComb et al. 2000(McComb et al. , 2001. Increased instances of regular fission-fusion patterns, and the occurrence of such instances with an increasing number of individuals, may reflect the growth of a translocated calf's information network and their settling into a social pattern reflective of fluctuating ecological conditions. ...
Conservation translocations have the potential to strengthen populations of threatened and endangered species, but facilitating integration of translocated individuals with resident populations remains a substantial challenge. Developing functional social relationships like cooperative partnerships or establishing clear dominance hierarchies may be critical to integration of released individuals. Developing such relationships has not received much attention in translocation research, especially for long-lived, socially complex animals for which establishment and navigation of social environments is often a lengthy process that requires sustained monitoring to understand. Here, we present a case study of the social associations of African savannah elephant ( Loxodonta africana ) calves that have been rehabilitated and released into a fenced wildlife sanctuary in northern Kenya with a resident population of elephants. We use focal follows of interactions pre-release and GPS tracking post-release to quantify social associations of calves with each other and with resident elephants at the release site. We demonstrate how this approach supports translocation monitoring by capturing temporal trends in social patterns within and between release cohorts and among released elephants and wild elephants already resident at the site during a transitional soft release period. Our results show that initial post-release social behavior of rehabilitated calves is related to histories of interaction with familiar individuals and cohort membership and that released calves increased their associations with residents over time. This information provides new behavioral insights for guiding elephant release projects, like the strength of relationships within and among release cohorts, the time to integration with the resident population, and the occurrence and increased incidence of societal fission–fusion. Further, this study provides an example of the utility of animal behavior research to achieve and assess progress towards conservation objectives, and to develop monitoring tools for conservation managers.
... In addition, several studies in non-human animals have demonstrated individual vocal recognition [63][64][65][66][67][68] (but see [69]). Some species are clearly capable of recognizing numerous individual callers (approximately 100 individuals in African elephants [70]) and even associate callers with traits lying on multiple axes (such as rank and kinship [71,72]). Hyenas clearly have the cognitive capacity to recognize and remember clan-mates as individuals [28,30,73]; perhaps the development of a group signature is more costly than the memory required to recognize 125 + voices. ...
In animal societies, identity signals are common, mediate interactions within groups, and allow individuals to discriminate group-mates from out-group competitors. However, individual recognition becomes increasingly challenging as group size increases and as signals must be transmitted over greater distances. Group vocal signatures may evolve when successful in-group/out-group distinctions are at the crux of fitness-relevant decisions, but group signatures alone are insufficient when differentiated within-group relationships are important for decision-making. Spotted hyenas are social carnivores that live in stable clans of less than 125 individuals composed of multiple unrelated matrilines. Clan members cooperate to defend resources and communal territories from neighbouring clans and other mega carnivores; this collective defence is mediated by long-range (up to 5 km range) recruitment vocalizations, called whoops. Here, we use machine learning to determine that spotted hyena whoops contain individual but not group signatures, and that fundamental frequency features which propagate well are critical for individual discrimination. For effective clan-level cooperation, hyenas face the cognitive challenge of remembering and recognizing individual voices at long range. We show that serial redundancy in whoop bouts increases individual classification accuracy and thus extended call bouts used by hyenas probably evolved to overcome the challenges of communicating individual identity at long distance.
... They show greater inquisitive behaviour towards deceased conspecifics than heterospecifics [26]. A study on African elephants showed that the herd members reacted to playback calls of former members (a dead female that had died during the study and another female that had left the natal herd) suggesting long-term memory and vocal recognition of individuals [27]. ...
Documenting the behavioural repertoire of an animal species is important for understanding that species' natural history. Many behaviours such as mating, parturition and death may be observed only rarely in the wild due to the low frequency of occurrence, short duration and the species' elusiveness. Opportunistic documentation of rare behaviours is therefore valuable for deciphering the behavioural complexity in a species. In this context, digital platforms may serve as useful data sources for studying rare behaviours in animals. Using videos uploaded on YouTube, we document and construct a tentative repertoire of thanatological responses (death-related behaviours) in Asian elephants ( Elephas maximus ). The most frequently observed thanatological responses included postural changes, guarding/keeping vigil, touching, investigating the carcass, epimeletic behaviours and vocalizations. We also describe some infrequently observed behaviours, including carrying dead calves by adult females, re-assurance-like behaviours and attempts to support dying or dead conspecifics, some of which were only known anecdotally in Asian elephants. Our observations indicate the significance of open-source video data on digital platforms for gaining insights into rarely observed behaviours and support the accumulating evidence for higher cognitive abilities of Asian elephants in the context of comparative thanatology.
... Male African savanna elephants use similar 'musth rumbles,' which are low-frequency calls that advertise sexual state [42,101,102]. Elephants also respond to conspecific vocalizations either to find associated kin for safety or to avoid unknown adversaries [90,103,104]. Thus, acoustic information can be beneficial for both familiar and unfamiliar interactions. ...
Elephants are well known for their socio-cognitive abilities and capacity for multi-modal sensory perception and communication. Their highly developed olfactory and acoustic senses provide them with a unique non-visual perspective of their physical and social worlds. The use of these complex sensory signals is important not only for communication between conspecifics, but also for decisions about foraging and navigation. These decisions have grown increasingly risky given the exponential increase in unpredictable anthropogenic change in elephants’ natural habitats. Risk taking often develops from the overlap of human and elephant habitat in Asian and African range countries, where elephants forage for food in human habitat and crop fields, leading to conflict over high-quality resources. To mitigate this conflict, a better understanding of the elephants’ sensory world and its impact on their decision-making process should be considered seriously in the development of long-term strategies for promoting coexistence between humans and elephants. In this review, we explore the elephants’ sensory systems for audition and olfaction, their multi-modal capacities for communication, and the anthropogenic changes that are affecting their behavior, as well as the need for greater consideration of elephant behavior in elephant conservation efforts.
... Although not all differences found between individuals encode information for the receiver (Townsend et al. 2010), investigation of individual vocal recognition has been demonstrated in the call types of a few species, for example, elephants (McComb et al. 2000), zebra finches (Taeniopygia guttata, Elie and Theunissen 2018), and African penguins (Spheniscus demersus, Favaro et al. 2015). Our work might offer a novel approach on the chorus howl, since regardless of the acoustic features of vocal types, it highlights the fact that wolves have individually unique vocal behaviors when they participate in a chorus howl. ...
Wolf packs perform group vocalizations called chorus howls. These acoustic signals have a complex structure and could be involved in functions such as strengthening of social bonds, territory advertisement, or spacing between packs. We analyzed video recordings of 46 chorus howls emitted by 10 packs of wolves held in captivity, in order to investigate whether sex, age, social status, pack, or individual influence the way wolves participate in a chorus. We found that, during a chorus, wolves vocalized 63% of the time, with the howl being the most common vocalization (36% of the chorus duration), followed by woa (13.5%), other vocalizations (11.8%), and bark (1.7%). The main factor affecting the vocal behavior of wolves was age, since young wolves vocalized less and uttered shorter acoustic signals than adults. The discriminant analysis carried out with the wolves of Cañada Real pack assigned 89.3% of the cases to the correct individual, which is much better than the assignment expected by chance, suggesting that individuals could have a unique vocal usage during a chorus howl, mainly due to the use of howls and woa-woa howls. Based on our results, we propose that in the context of a chorus the woa-woa howl is important, although further research is needed to address this issue properly.
... Vocalisations have been found to serve a number of purposes; for example, they facilitate recognition of kin [1][2][3][4][5][6][7], warn of predators [8,9], confirm territories [10,11], solicit sexual attention from conspecifics [12][13][14] and permit assessment of rivals [15]. Koalas, Phascolarctos cinereus, are vocal marsupials, using bellows to communicate in vast Australian eucalypt forests. ...
Effective conservation strategies rely on knowledge of seasonal and social drivers of animal behaviour. Koalas are generally solitary and their social arrangement appears to rely on vocal and chemical signalling. Male koala vocalisations, known as bellows, are believed to be closely related to their breeding behaviour. Previous research suggests that oestrous female koalas use bellows to locate unique males to mate with, and that males can similarly use bellows to evaluate the physical attributes of their peers. We tested the behavioural responses of 20 free ranging koalas to bellow recordings collected from small (<6 kg) and large (>8.5 kg) adult male koalas. Individual koala movement was reported by hourly-uploaded GPS coordinates. We report evidence of intra-male competition, with adult males approaching bellow playbacks, particularly those from small-sized males. In contrast, males under three years of age were averse to the playbacks. No patterns in the response of females were detected. Our results provide the strongest evidence yet that bellows are primarily a means by which males occupy and control space during the breeding season. Future studies are required to see if female response to bellows depends on their reproductive status.
... Interest in familiarity recognition in non-human animals, based on voice, has exploded in the past few decades. Studies have documented innate voice recognition abilities in the social rodent (degu or brush-tailed rat) (Fuchs et al., 2010), in deer (Charlton et al., 2007;Torriani et al., 2006), in goats (Terrazas et al., 2003), in dogs (Adachi et al., 2007), in sheep (Sèbe et al., 2010;Searby & Jouventin, 2003), in African elephants (McComb et al., 2002), in Australian sea lions (Pitcher et al., 2010), in wolves (Goldman et al., 1995), in mares (Wolskia et al., 1980), in seals (Aubin et al., 2015;Charrier et al., 2001Charrier et al., , 2003Insley, 2001), and in parrots (Berg et al., 2011). Individual vocal recognition skills of numerous non-human primates have come to light: macaques (Fischer, 2004;Masataka, 1985), rhesus monkeys (Hansen, 1976;Rendall et al., 1996), vervet monkeys (Cheney & Seyfarth, 1980), and baboons (Cheney & Seyfarth, 1999). ...
The vocal pattern from its very beginning in evolution and the role of familiarity in vocal communication.
... Hosts that live in stable social groups can exhibit contact processes that do not track with conventional density-dependent expectations, imposing a form of behaviorally mediated frequency dependence with knock-on effects for pathogen transmission (e.g., Cross et al. 2013;Manlove et al. 2014). Environmental correlates of group stability remain relatively underexplored (with the exceptions of environmentally driven soundscapes, lines-of-sight, and shared small space use, e.g., McComb et al. 2000;Strandburg-Peshkin et al. 2013;Pinter-Wolman et al. 2017 respectively). A better general understanding of how the environment relates to group cohesion and fission-fusion rates would be useful. ...
Environment drives the host movements that shape pathogen transmission through three mediating processes: host density, host mobility, and contact. These processes combine with pathogen life-history to give rise to an “epidemiological landscape” that determines spatial patterns of pathogen transmission. Yet despite its central role in transmission, strategies for predicting the epidemiological landscape from real-world data remain limited. Here, we develop the epidemiological landscape as an interface between movement ecology and spatial epidemiology. We propose a movement-pathogen pace-of-life heuristic for prioritizing the landscape’s central processes by positing that spatial dynamics for fast pace-of-life pathogens are best-approximated by the spatial ecology of host contacts; spatial dynamics for slower pace-of-life pathogens are best approximated by host densities; and spatial dynamics for pathogens with environmental reservoirs reflect a convolution of those densities with the spatial configuration of environmental reservoir sites. We then identify mechanisms that underpin the epidemiological landscape and match each mechanism to emerging tools from movement ecology. Finally, we outline workflows for describing the epidemiological landscape and using it to predict subsequent patterns of pathogen transmission. Our framework links transmission to environmental context, providing a scaffold for mechanistically understanding how environmental context can generate and shift existing patterns in spatial epidemiology.
... Each form of social learning increases the complexity of a communication system. Elephants naturally use their vocal skills for individual recognition [16], group cohesion and coordination with the rumble being the dominating call type [3]. Neonates rumble (though different from adults) soon after birth [3,17]. ...
Elephants exhibit remarkable vocal plasticity, and case studies reveal that individuals of African savannah ( Loxodonta africana ) and Asian ( Elephas maximus ) elephants are capable of vocal production learning. Surprisingly, however, little is known about contextual learning (usage and comprehension learning) in elephant communication. Usage learning can be demonstrated by training animals to vocalize in an arbitrary (cue-triggered) context. Here we show that adult African savannah elephants ( n = 13) can vocalize in response to verbal cues, reliably producing social call types such as the low-frequency rumble, trumpets and snorts as well as atypical sounds using various mechanisms, thus displaying compound vocal control. We further show that rumbles emitted upon trainer cues differ significantly in structure from rumbles triggered by social contexts of the same individuals ( n = 6). Every form of social learning increases the complexity of a communication system. In elephants, we only poorly understand their vocal learning abilities and the underlying cognitive mechanisms. Among other research, this calls for controlled learning experiments in which the prerequisite is operant/volitional control of vocalizations.
This article is part of the theme issue ‘Vocal learning in animals and humans’.
... investigated antiphonal calling between affiliated females -a call and response pattern that is frequently used, potentially for the maintenance of the group, facilitation of cooperative tasks and for advertising emotional states. The calls are all distinct, providing clues to identity.McComb et al. (2000) determined that elephants can recognise up to 100 other elephants in their extended families, building up their knowledge as they grow older and encounter more family members. ...
This thesis explores the challenge for humans of designing and crafting interactive enrichment systems for elephants housed in captivity.
Captive elephants may have limited opportunity to express a full range of natural behaviours and therefore benefit from well-designed environmental enrichment. We asked whether technology could support the design and development of novel enrichment for elephants and investigated what kinds of technology-enabled systems would hold their interest. Crucially, these systems were designed to provide the elephants with opportunities to make and enact choices – giving them more control over what happened in their environment.
After researching wild elephant lifestyle and characteristics, our fieldwork started with an ethnographic study of captive elephants. We then followed an exploratory approach: Research through Design and Craft. Over several years, a range of interactive systems were crafted for elephants. Each device included embedded technology that enabled elephant interactions to be captured and mapped to associated system outputs. Elephants and their keepers were involved in this cyclical process, and the elephants’ reactions to the devices were noted and interpreted, giving rise to insights that informed the subsequent designs.
Analysis of the design and development of the enrichment systems revealed important interface attributes and design considerations that we describe in this document. Finally, we offer five contributions for the ACI community: (i) Research through Design and Craft methodology, which was developed and tested over several years; (ii) ZooJam workshops, which were organised with colleagues over three years; (iii) six key principles of interaction design for ACI development – consistency, differentiation, graduation, specificity, multiplicity and affordance; (iv) an exploration of More than Human Aesthetics focusing on performative aesthetics; (v) a prototype deck of Concept Craft Cards that share theoretical and practical topics with other designers and developers.
... Elephants are sexually dimorphic where adult males weigh up to 6000 kg, which is twice the weight of adult females (Owen-Smith 1992). Adult females and their offspring of different ages live in fused family groups, usually accompanied by one mature male (McComb et al. 2000;Archie and Chiyo 2012). Young males are forced out of the family groups between the ages of 10-15 years and join bachelor groups or range independently (Shannon et al. 2006b;Chiyo et al. 2011). ...
Sexual differences in foraging behaviour of African elephant are comparatively well studied. However, the behaviour is known to vary between savannas due to differences in plant and herbivory communities which determine the level of forage selection and competitions. The sexual variation in foraging behaviour is attributed by sexual dimorphism, where male elephants are larger than females. The different body sizes result in divergent foraging strategies due to the differential scaling coefficients of metabolism and gut size, where the larger bodied individuals can tolerate greater quantities of low-quality forage. We studied the foraging behaviour of male and female elephants in Serengeti National Park, a nutrient-rich savanna in Tanzania, based on the forage selection and the scramble competition hypotheses. Data were collected for 2 months in 2014 by driving in road transects and make visual observations of browsing elephants within 50 m from the road. We recorded the number of bites taken per tree, parts of the tree browsed, browsing height, and tree species. Females targeted a wider range of wood species, browsing at lower heights compared to males. The sexes had a comparable length of browsing bouts, spending an average of 4 min per tree. The results support the scramble competition hypothesis through the feeding height stratification and the forage selection hypothesis through the higher diversity of tree species utilised by females. We suggest that sexual differences in forage requirements interact with forage quality and competing herbivore communities in shaping the foraging behaviour of elephants.
With the escalating challenges in captive elephant management, the study of elephant reintegration emerges as a pivotal area of research, primarily addressing the enhancement of animal welfare. The term ‘reintegration’ refers to the process of rehabilitating captive elephants to a natural system, allowing them to roam freely without intensive human intervention. There is a relative paucity of research addressing the behavioural adaptations post-reintegration, despite reintegration of over 20 elephants across various fenced reserves in South Africa. Our study centres on two distinct herds of reintegrated African elephants, monitoring their movement patterns in two South African reserves over a 57-month period post-release. The primary goal of the study was to establish whether the flexibility and adaptability of movement behaviour of reintegrated elephants can be considered as one of the indicators of determining the success of such an operation. The second aim of our study was to investigate if the reintegrated elephants demonstrated an adaptability to their environment through their hourly, daily, and seasonal ranging patterns after a period of free roaming that exceeded 4 years. Our findings indicated that reintegrated elephants, much like their wild counterparts (movement based on literature), displayed notable seasonal and diurnal variations in key movement parameters, such as utilisation distribution areas and reserve utilization. These patterns changed over time, reflecting an adaptive shift in movement patterns after several years of free roaming. Notably, the trajectory of changes in movement parameters varied between herds, indicating unique adaptation responses, likely resulting from differences in the reintegration process (familiarity of reserve, season of release, presence of wild elephants). Although our study is constrained by the limited number of reintegrated herds available for analysis, it underscores the potential of captive elephants to successfully adapt to a free-living environment, emphasising the promising implications of reintegration initiatives.
African (Bantu) philosophy conceptualizes morality through ubuntu, which emphasizes the role of community in producing moral agents. This community is characterized by practices that respond to and value interdependence, such as care, cooperation, and respect for elders and ancestral knowledge. While there have been attributions of morality to nonhuman animals in the interdisciplinary animal morality debate, this debate has focused on Western concepts. We argue that the ubuntu conception of morality as a communal practice applies to some nonhuman animals. African elephant communities are highly cooperative and structured around elders; they alloparent, protect their communities, mourn their dead, and pass on cultural knowledge between generations. Identifying these as important moral practices, ubuntu provides a theoretical framework to expand our ethical concern for elephants to their communities. In practice, this will deepen our understanding of the wrongness of atrocities like culling for population management or trophy hunting.
La présente recherche tente d'étoffer une compréhension plus large et intégrative à
l'égard des communications vocales non verbales et paraverbales, de leurs rôles et
implications dans le développement psychoaffectif, et de leurs potentialités dans le
contexte plus précis des psychothérapies relationnelles à visées développementales.
Dans une démarche d'enquête s'apparentant à une méta-analyse inspirée de
théorisation ancrée, des données variées et issues de différents domaines sont
étudiées, analysées et rassemblées de manière à faire émerger une perspective
cohérente et unifiée de tout ce qui transmet par la voix au-delà de la parole, un
phénomène par ailleurs très peu étudié dans la littérature en psychologie.
Pour commencer, une exploration détaillée de l'évolution neurocognitive, vocale et
sociale menant à l'humain permet de préciser les fonctions primaires de la voix au
sein de notre espèce, plus particulièrement au niveau de l'attachement, de la
régulation émotionnelle, de l'organisation des groupes et de la transmission de
compétences sociales fondamentales. Les bénéfices et risques liés à la distinction
graduelle de deux canaux vocaux parallèles – verbal et non verbal – sont également
discutés. De là, un survol des usages de la voix complémentaires à la parole au cours
de l'histoire occidentale sert à exposer différentes manières dont l'expression vocale
a pu servir le bien-être individuel et collectif au fil du temps, et une analyse plus
systémique du phénomène vocal et de ses différentes facettes vient clarifier ses
racines profondément culturelles. S'en suit une présentation des utilisations de la voix
dans certaines approches de soin plus actuelles, laquelle permet d'en arriver à
exposer le manque flagrant de connaissances sur le sujet en psychologie et l'absence
complémentaire de méthodes vocales se démarquant du dialogue verbal dans les
approches psychothérapeutiques traditionnelles.
Pour tenter de combler ces lacunes, six approches usant de la voix à des fins de mieux-être et de croissance personnelle – dont quatre plus expressément
psychothérapeutiques – sont présentées de manière à la fois synthétique et
structurée afin de bien cerner leur logique et leur mécanique d'action respectives.
Une proposition conceptuelle intégrative est ensuite élaborée, qui reprend certains
des principaux thèmes retrouvés dans ces approches et les assemble avec des idées
et théories éprouvées en psychologie développementale, en neuropsychologie et en
neurosciences affectives. Cette contribution de l'auteur comporte deux volets
principaux et complémentaires. D'abord, un modèle du développement neuropsychoaffectif primaire donnant leur juste place aux communications vocales,
dès le développement intra-utérin, et précisant leurs intrications avec les mécanismes
dissociatifs pouvant se constituer au cours de la croissance individuelle. Ensuite, une
étude du travail psychothérapeutique sous certaines facettes – notamment
développementales – mettant en lumière la pertinence et l'utilité des méthodes
vocales non conventionnelles. Les implications sur le plan de la formation et des
responsabilités du thérapeute sont également abordées, en cohérence avec le
modèle théorique proposé, afin de donner quelques pistes aux praticiens intéressés
à introduire des outils d'intervention psychovocaux à leur approche.
Il ressort de ce travail que l'interaction vocale non verbale et paraverbale s'avère
fondamentale à l'expérience du lien dans toute relation d'attachement, et ce tout au
long de la vie. En ce sens, l'utilisation de techniques et de méthodes vocales variées
et ajustées aux circonstances peut permettre de renforcer la mécanique de résonance
intersubjective, en particulier pour soutenir l'alliance thérapeutique, la régulation
émotionnelle lors de régressions ou d'épisodes plus difficiles (par exemple où le client
rencontre ses traumatismes et blessures profondes), l'intégration neuronale plus
globale, ainsi que pour favoriser les expériences de communion et de plaisir partagé
dans la dyade thérapeutique.
This research attempts to develop a broader and integrative understanding of
nonverbal and paraverbal vocal communications, their roles and implications in
psycho-emotional development, and their potential in the more specific context of
developmental relational psychotherapy. In a survey approach similar to a meta-
analysis inspired by grounded theory, various data from different domains are
studied, analyzed and collected in such a way as to bring out a coherent and unified
perspective of all that transmits by the voice beyond the spoken word, a phenomenon
that is otherwise poorly studied in psychology literature.
To start with, a detailed exploration of the neurocognitive, vocal and social evolution
leading to the human allows clarifying the primary functions of the voice within our
species, more particularly in regard to attachment, emotional regulation, organization
within groups and the transmission of fundamental social skills. The benefits and risks
of gradual distinction of two parallel vocal channels - verbal and nonverbal - are also
discussed. From here, an overview of different vocal behaviours in Western history is
used to describe ways in which vocal expression has served individual and collective
well-being over time, and a more systemic analysis of the vocal phenomenon and its
different facets helps to understand its deeply cultural roots. This is followed by a
presentation of the uses of the voice in some of the more contemporary approaches
to care, which then leads to the clarification of the glaring lack of knowledge on the
subject in psychology and the additional absence of vocal methods that stand out
from the verbal dialogue in traditional psychotherapy.
In an attempt to fill these gaps, six methods using some kind of vocal work for the
sake of wellness and personal growth – four of which being explicitly
psychotherapeutic – are presented in a synthetic and structured way in order to
understand their logic and mechanics. An integrative conceptual proposal is then
developed, which takes up some of the main themes found in these approaches and
assembles them with proven ideas and theories in developmental psychology,
neuropsychology and affective neuroscience. This more substantial contribution by
the author has two main and complementary components : first, a model of primary
neuropsychoaffective development giving a proper place to vocal communication,
from intrauterine development, and specifying their entanglements with the
dissociative mechanisms that can be formed during individual growth; second, a more
in-depth study of psychotherapeutic work – seen in itself as a developmental process
in some facets that can be more directly addressed in a relevant and fruitful way
using unconventional vocal methods. The implications for the therapist's training and
responsibilities are also explored in line with the proposed theoretical model, in order
to give some pointers to practitioners interested in introducing psychovocal
intervention tools to their approach. It is clear from this work that nonverbal and paraverbal vocal interaction is fundamental to the experience of bonding in any attachment relationship throughout life. In this sense, the use of varied and context-specific vocal techniques and methods can help reinforce intersubjective resonance mechanisms, therapeutic alliance, emotional regulation during regressions or more challenging episodes (for example where a client encounters his trauma and deep wounds), neuronal integration, and to foster the experience of communion and shared pleasure in the therapeutic dyad.
Bottlenose dolphins are a large-brained, long-lived, highly social species, operating within a fission-fusion society characterized by broad multi-level social networks, extensive care giving and teaching of offspring, cooperative and diverse hunting tactics, long-term alliances, and learned vocal signals that broadcast an individual’s identity, can be used in referential exchanges and can be imitated by close associates. Observations of behavior and social interactions in the wild suggest that social cognition in the bottlenose dolphins is well developed. Over the past thrity years, experimental studies have revealed that bottlenose dolphins have decades long social memories of associates, can develop a broad concept of imitation that extends to arbitrary novel sounds and social behaviors presented in a variety of contexts as well as to self-initiated behaviors. Dolphins have also been shown to be able to learn about and appreciate the social requisites of cooperative behavior, can spontaneously understand the referential character of human-initiated social signals involving pointing and gazing, and can employ pointing productively in communicative exchanges with humans to achieve goals. Collectively, dolphin social-cognition abilities are sophisticated and similar in several aspects to those of other species living within complex social networks, such as elephants, chimpanzees, and humans.
Long-term memory has clear advantages but also has neurological and behavioral costs. Given these opposing selection pressures, understanding how long memories last can shed light on how memory enhances or constrains animals' abilities to exploit their niches. Although testing memory retention in wild animals is difficult, it is important because captive conditions do not reflect the complex cognitive demands of wild environments, and long-term captivity changes the brain. Here, we trained wild-caught frog-eating bats ( Trachops cirrhosus ) to find prey by flying to a novel acoustic cue, released them back into the wild, and then re-captured some of them 1-4 years later. When re-tested, all eight 'experienced' bats that previously learned the novel prey sounds flew to those sounds within seconds, whereas 17 naïve bats tested with the same sounds showed weak responses. Experienced bats also showed behavior indicating generalization of memories between novel sounds and rewards over time. The frog-eating bat's remarkably long memory for novel acoustic cues indicates that an ability to remember rarely encountered prey may be advantageous for this predator, and suggests hitherto unknown cognitive abilities in bats.
Loud, long-distance calls serve varied functions across animal species including marking territory, attracting mates and signalling one's identity. Here, we examined the types of sender- and context-specific information encoded in the howls of captive timber wolves, Canis lupus. We analysed 913 howls from nine individuals across three packs and investigated whether howl structure varied consistently as a function of phenotypic factors (age class, sex, pack and identity of the caller) in addition to the context in which the call was produced: specifically, whether the call was produced in a ‘spontaneous’ context just after sunrise or was ‘elicited’ by the absence of a group member. Calls were correctly classified by individual identity and production context, but not by any other factors. Principal components analyses indicated that individual differences were primarily associated with frequency-based measures, whereas acoustic variation between production contexts was associated with a variety of frequency-, intensity- and energy-based measures. Recognition of individual differences in vocalizations is likely to be important for navigating social relationships in wolves and further work is required to determine which life history factors may shape these individual differences. Differences resulting from production context are suggestive that these howl variants may serve different functions. The extent to which these individual and contextual differences are understood by receivers remains an open question.
Dominance hierarchies typically emerge in systems where group members regularly encounter and compete for resources. In birds, the ‘open’ and dynamic structure of foraging groups may prevent the emergence of structured hierarchies, although this assumption have hardly been tested. We report on agonistic data for ravens Corvus corax , collected over two 18-month periods for 183 marked individuals of a wild (fluid) population and 51 birds from six captive (stable) groups. We show that the dominance structure (steep and transitive) in wild foraging groups is strikingly similar to that found in captivity. In the wild, we found that higher ranks are mainly occupied by males, older and more aggressive individuals that also tend to receive fewer aggressions. Exploring the mechanisms sustaining the wild dominance structure, we confirmed that males are more aggressive than females and, with age, tend to receive fewer aggressions than females. Males that are about to leave the foraging groups for some months are less aggressive than newcomers or locals, while newcomers are specifically targeted by aggressions in their first year (as juveniles). Taken together, our results indicate that the socially dynamic conditions ravens face during foraging do not hinder, but provide opportunities for, using (advanced) social cognition.
This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.
Communication is the transmission of information from one animal to another. Although communication can be as complex as any set of words ever put on paper, it can also be as simple as a receptor sensing a molecule emitted from another living organism. Indeed, such receptors are hypothesized to be the evolutionary antecedent of communication. From that point onward, communication has evolved to use a variety of modes, including chemical, visual, auditory, tactile, and more. The world of communication that behavioral studies reveal ranges from warning coloration to infrasonic elephant communication to electrical pulses and poses a challenge: what signals do animals use that are beyond human sensory ability?
The social complexity hypothesis (SCH) for communication states that the range and frequency of social interactions drive the evolution of complex communication systems. Surprisingly, few studies have empirically tested the SHC for vocal communication systems. Filling this gap is important because a co-evolutionary runaway process between social and vocal complexity may have shaped the most intricate communication system, human language. We here propose the African elephant Loxodonta spec. as an excellent study system to investigate the relationships between social and vocal complexity. We review how the distinct differences in social complexity between the two species of African elephants, the forest elephant L. cyclotis and the savanna elephant L. africana, relate to repertoire size and structure, as well as complex communication skills in the two species, such as call combination or intentional formant modulation including the trunk. Our findings suggest that Loxodonta may contradict the SCH, as well as other factors put forth to explain patterns of vocal complexity across species. We propose that life history traits, a factor that has gained little attention as a driver of vocal complexity, and the extensive parental care associated with a uniquely low and slow reproductive rate, may have led to the emergence of pronounced vocal complexity in the forest elephant despite their less complex social system compared to the savanna elephant. Conclusions must be drawn cautiously, however. A better understanding of vocal complexity in the genus Loxodonta will depend on continuing advancements in remote data collection technologies to overcome the challenges of observing forest elephants in their dense rainforest habitat, as well as the availability of directly comparable data and methods, quantifying both structural and contextual variability in the production of rumbles and other vocalizations in both species of African elephants.
The social behaviour of many species of non-human primates suggests a capacity for both individual and kin recognition. In these species, the ability to signal and perceive identity at a distance may be an important adaptation facilitating intra-group social communication. Variation in vocalizations is hypothesized to provide a basis for this ability. Playback experiments were conducted to test for vocal recognition of contact calls between adult female rhesus macaques,Macaca mulatta. Single-trial playbacks of the contact call of either a matrilineal relative or a familiar, non-relative group member were used to test for discrimination of kin from non-kin. Females responded significantly faster and longer to the contact calls of matrilineal relatives. A habituation–discrimination paradigm was then used to test for individual recognition. Females habituated to successive presentations of different exemplars of the contact calls of one matrilineal relative, then showed a significant rebound in response to the subsequent presentation of a contact call from a second matrilineal relative. These results indicate an ability for vocal recognition of both individuals and kin. Females' responses to playbacks suggested the additional possibility for categorical recognition of matrilineal kinship, or its correlates.
Group size covaries with relative neocortical volume in nonhuman primates. This regression equation predicts a group size for modern humans very similar to that for hunter-gatherer and traditional horticulturalist societies. Similar group sizes are found in other contemporary and historical societies. Nonhuman primates maintain group cohesion through social grooming; among the Old World monkeys and apes, social grooming time is linearly related to group size. Maintaining stability of human-sized groups by grooming alone would make intolerable time demands. It is therefore suggested (1) that the evolution of large groups in the human lineage depended on developing a more efficient method for time-sharing the processes of social bonding and (2) that language uniquely fulfills this requirement. Data on the size of conversational and other small interacting groups of humans accord with the predicted relative efficiency of conversation compared to grooming as a bonding process. In human conversations about 60% of time is spent gossiping about relationships and personal experiences. Language may accordingly have evolved to allow individuals to learn about the behavioural characteristics of other group members more rapidly than was feasible by direct observation alone.
We conducted 58 playback experiments with free-ranging African elephants in Etosha National Park, Namibia, to estimate the distance over which some of their low-frequency calls are audible to other elephants. We broadcast pre-recorded elephant calls to elephants that were 1.2 and 2.0 km from the speaker while making simultaneous video and audio recordings of their behavior. In order to reduce the risk of habituation, we used a variety of call types as stimuli. Elephants responded to playbacks at both 1.2 and 2.0 km, with a full response consisting of the elephant vocalizing, lifting and spreading its ears, remaining motionless in this position (‘freezing’), moving the head from side to side (‘scanning’) and, in the case of males responding to female estrous calls, orienting to and finally walking 1 km or more towards the loudspeaker.
We analyzed our data quantitatively for three of these responses. The occurrence of each behavior increased substantially immediately after playbacks.
Owing to limitations of the loudspeaker, we were only able to broadcast calls at half the sound pressure level (i.e. —6dB) of the strongest calls we have recorded. Since sound at the frequencies of these calls is predicted to suffer from little, if any, attenuation in excess of that caused by spherical spreading, we estimate these calls to be audible to elephants at least 4 km from the source (twice the distance over which we documented responses).
These results are consistent with the hypothesis that the very low-frequency calls of elephants function in communication between individuals and groups of elephants separated by distances of several kilometers.
Vocal exchanges within pods were dominated by repetitious, discrete calls. Pods each produced 7-17 (mean 10.7) types of discrete calls. Individuals appear to acquire their pod's call repertoire by learning, and repertoires can persist with little change for >25 yr. In the resident population, the 16 pods formed four distinct acoustic associations, or clans, each having a unique repertoire of discrete calls, or vocal tradition. It is proposed that each clan comprises related pods that have descended from a common ancestral group. New pods formed from this ancestral group through growth and matrilineal division of the lineage. -from Author
Measured vertical profiles of temperature and wind an used to model infrasound propagation over a representative high savanna habitat typically occupied by the African elephant, Loxodonta Africana, to predict calling distance and area as a function of the meteorological variables, The profiles were measured up to 300 m above the surface by tethered balloon-borne instruments in Etosha National Park, Namibia, during the late dry season. Continuous local surface layer measurements of wind and temperature at 5 and 10 m provide the context for interpreting the boundary layer profiles. The fast field program (FFP) was used to predict the directionally dependent attenuation of a 15-Hz signal under these measured atmospheric conditions, the attenuation curves are used to estimate elephant infrasonic calling range and calling area, Directionality and calling range are shown to be controlled by the diurnal cycle in wind (shear) and temperature. Low-level nocturnal radiative temperature inversions and low surface wind speeds make the early evening the optimum time for the transmission of low-frequency sound at Etosha, with range at a maximum and directionality at a minimum, As the night progresses, a nocturnal low-level wind maximum (jet) forms, reducing upwind range and calling area, The estimated calling area drops rapidly after sunrise with the destruction of the inversion, Daytime calling areas are usually less than 50 km(2), while early evening calling areas frequently exceed 200 km(2) and are much less directional, This marked diurnal cycle will be present in any dry savanna climate, with variations due to local topography and climate, Calling range and low-frequency sound propagation cannot be effectively understood without knowledge of meteorological controls
Male singing behaviour correlates with extra-pair success in several passerine birds. Singing interactions during territorial contests provide relative information on the males involved. Such information may be important in female extra-pair behaviour and eavesdropping on singing interactions among males may allow females to make such relative assessments. We used interactive playback to instigate singing contests with male great tits during the peak fertile period of their mate in an attempt to alter females' assessment of mates' quality relative to neighbours (potential extra-pair partners). We escalated a contest to one male (by overlapping his songs) and then subsequently de-escalated a contest (by alternating) to a neighbour. Intrusions onto neighbouring territories by females mated to either treatment male were then monitored. Females mated to escalation treatment males were more likely to intrude following playbacks than females mated to de-escalation treatment males. Although the absolute song output of males did not differ between treatments, males produced more song relative to playback in de-escalation treatments and relative song output was positively correlated with female intrusions. Therefore, female great tits eavesdrop on singing interactions and change their visitation rates to neighbouring territories according to their mate's singing performance relative to neighbours.
Atmospheric conditions conducive to long-range transmission of low-frequency sound as used by elephants are found to exist in the Etosha National Park in Namibia during the late dry season. Meteorological measurements show that strong temperature inversions form at the surface before sunset and decay with sunrise, often accompanied by calm wind conditions during the early evening. These observations are used in an acoustic model to determine the sensitivity of infrasound to the effects of (a) the strength, thickness and elevation of temperature inversions, and (b) the growth and decay of an inversion typical of dry, elevated African savannas. The results suggest that the range over which elephants communicate more than doubles at night. Optimum conditions occur 1-2 h after sunset on clear, relatively cold, calm nights. At these times, ranges of over 10 km are likely, with the greatest amplification occurring at the lowest frequency tested. This strong diurnal cycle in communication range may be reflected in longer-lasting changes in weather and may exert a significant influence on elephant behaviour on time scales from days to many years.
Despite evidence from several bird, fish and mammal species that listeners can discriminate between the vocalizations of familiar and unfamiliar adult conspecifics, direct links between discriminatory abilities and fitness benefits have been difficult to identify. In free-ranging populations of African lions (Panthera leo), females with cubs face a substantial threat from one particular category of unfamiliar individuals: infanticidal males. Here we use playback experiments to demonstrate that females with cubs can distinguish immediately between roars from their own resident males (the fathers of the cubs) and those from unfamiliar, potentially infanticidal males. Although they remain relaxed when played roars from resident males, they immediately become agitated on hearing unfamiliar males and retreat rapidly with their cubs if the latter have reached about 4.5 months of age. These responses are not simply a function of the roarers being unfamiliar, for when played the roars of unfamiliar females, females with cubs consistently approach the loudspeaker. Furthermore, females often move toward the cubs in response to playbacks of unfamiliar males but not in response to playbacks of unfamiliar females or resident males. Our results suggest how females with cubs might, by quickly detecting and categorizing unfamiliar intruders within their territory, protect their cubs from infanticidal males and expel intruding females. Distinguishing between individuals on the basis of their vocal characteristics could therefore confer direct fitness benefits on discriminating lionesses.
Low-level vertical changes in temperature and wind exert powerful and predictable influences on the area ensonified by animal vocalizations. Computer modelling of low-frequency sound propagation in measured atmospheric conditions predicts that the calls of the savanna elephant at these frequencies can have ranges exceeding 10 km and that the calls will be highly directional in the presence of wind shear. Calling area is maximized under temperature inversions with low wind speeds. Calling area changes substantially over 24 h periods; on any given day, the calling area undergoes an expansion and contraction which may be as large as one order of magnitude. This cycle is modulated by topography, regional weather patterns, seasonality and possibly by climate variation. Similar influences affect the somewhat higher-frequency calls of lions and may be a selective pressure towards their crepuscular and nocturnal calling behaviour. Coyotes and wolves, which also live in areas with strong and prevalent nocturnal temperature inversions, show similar calling patterns, maximizing their chances of being heard over the longest possible distances. The pronounced dawn and evening vocalization peaks in other animals including birds, frogs and insects may reflect the same influences in combination with other factors which selectively limit high-frequency sound propagation. Atmospheric conditions therefore need to be taken into account in many field studies of animal behaviour. A simplified method for estimating sound propagation during field studies is presented.
Territorial systems are characterized by the relative longevity and stability of interactions between neighbouring individuals. Two abilities of signal receivers that can be seen as adaptations increasing the efficiency of territory defence will be discussed: identifying neighbouring individuals and ranging (i.e. determining the distance to) signallers. The costs involved in such discriminations will also be outlined. Although signalling has been traditionally considered as occurring between two individuals (signaller and receiver), long-range signals will be received by many individuals. In territorial systems a group of neighbours could be considered as a communication network: consisting as its simplest of a signaller and a number of receivers. The scope for low cost, low-risk information gathering in such networks by eavesdropping will be discussed with particular reference to territorial songbirds and electric fish.
In macaques and baboons, scream vocalizations play a major role in the recruitment of allies against agonistic opponents. Pigtail macaques make use of 4 acoustically distinct scream types, with each associated with a particular agonistic context (defined in terms of the opponent's relative dominance rank and the intensity of the aggression). Information about caller identity must also be encoded in recruitment screams if spatially distant allies are to make decisions about intervention. In this study, the agonistic screams of pigtail macaques were analyzed for evidence of vocal signatures that may serve to identify matrilineal kin groups. Maternal genealogical relationships were known for all individuals in the 56 member study group. Direct discriminant analysis was used to classify calls of individuals on the basis of their acoustic structure to one of 3 groups defined by matrilineal relatedness (two homogeneous groups, or matrilines, and one heterogeneous control group). Two scream types associated with higher-ranking opponents were analyzed separately: contact aggression screams and noncontact screams. A highly significant proportion of calls was classified to the correct matrilineal group for both scream classes. The acoustic basis for matrilineal vocal signatures in these calls apparently exists. Efficient vocal communication may require monkeys to classify group members at different levels, depending upon the degree of specificity needed.
The contexts and functions of several loud mangabey vocalizations, particularly the "whoopgobble", were investigated observationally and experimentally. Whoopgobbles are notable for their audibility and distinctiveness over long distances, their temporal pattern of delivery, and particularly their stereotypy and individual distinctiveness. On the other hand, contexts of and responses to these vocalizations are variable and sometimes nonobvious. In order to control context and more systematically investigate response, an experimental method involving playback of recorded vocalizations was developed. Although precautions against habituation were necessary, mangabey responses to playbacks were clearcut and repeatable. Answering vocalizations, changes in group movement, and changes in the dispersion of individuals within a group occurred only in response to mangabey vocalizations. Whoopgobble playbacks provoked a pattern of response, including most notably the rapid approach of one adult male (the "RA" male) from each group, which was specific to this call. Playback of whoopgobbles between 100 and 600m from mangabey groups indicated that this call does transmit information regarding the identity of the vocalizing individual and group over these distances. Test groups moved away from neighboring- and unknown-group calls, but towards those of their own males - particularly those of RA males. RA males, on the other hand, do not approach calls of other males from their own groups. Within a group, whoopgobbles may thus increase cohesion and influence the direction of movements. Characteristics of whoopgobble form and context are discussed with regard to hypothesized functions of these and other forest monkey loud calls. Responses by free-ranging mangabeys to playback of the whoopgobble confirm its role in maintaining distance between groups. Response was found to be independent of group size, despite the fact that whoopgobble rate is closely related to this variable and thus could transmit such information. Since responses were also found to be independent of location within the home range, intergroup spacing among mangabeys appears not be be "territorial", site defense does not occur. Nevertheless, the central areas in at least some mangabey groups' home ranges were never penetrated by neighbors. Playback tests with black-and-white colobus and blue monkeys, among which territorial spacing has been reported, indicate that responses to loud calls have some degree of site-specificity among these species. But the mangabey pattern of intergroup spacing appears to result from a combination of low group density, site attachment within groups, and site-independent avoidance between groups. These results emphasize that spacing "system" and "pattern" are not necessarily equivalent; a given set of spacing behaviors can result in different spacing patterns under different ecological conditions, while a given pattern may be obtained by any of several behavioral means. Evidence for site-independent spacing in other primate species is discussed.
Individual recognition is widespread in the social behavior of birds. Three approaches have been employed, either singly or in combination, in the investigation of vocal recognition in birds: (1) field observation, (2) sound analysis, and (3) experiments to compare a bird's reactions to the sounds of different individuals. The chapter reviews the analysis of bird vocalizations and various experimental studies. Most analyses of bird vocalizations have focused on frequency time patterns. The experimental approaches carried out to investigate, whether birds can recognize one another individually by ear, have used playback of recorded sound. The individual recognition of voice in the laughing gull is discussed. The laughing gull (Lams atricilla) provides an example of a species, in which spacing out during breeding is much greater than it is in the guillemot. Individual recognition of voice in laughing gull has been investigated in two contexts: (1) interactions between adults during the incubation period and (2) interaction between parents and young during the period between hatching and fledging of the young.
Capabilities for long-term memory and recall of information have evolved in non-human animals primarily for special requirements such as for learning species-typical vocalizations and caching food 1-6. Long-term memory of individual social partners has, however, not been demonstrated previously for non-human animals. The ability to recognize individuals has important consequences for the evolution of intricate social interactions 7-11 and provides a basis for more sophisticated forms of cognition in animal societies 12,13. Recognition of social partners has been documented for territorial songbirds, which discriminate between songs of different neighbours 14-16 as well as between the songs of strangers and neighbours 17. Here I show that male hooded warblers (Wilsonia citrina, Parulinae) not only recognize their neighbours individually by song during the breeding season, but also retain the memory of neighbours' songs after an 8-month period during which they cease singing and migrate to Central America before they return to former breeding territories.
In my target article, I argued (1) that the relationship between neocortical size and group size in primates implies that there is a cognitive limit on the size of human groups, and (2) that time constraints forced the evolution of language as a more efficient means of bonding the large groups that humans evolved. The doubts about these claims raised by these additional commentaries largely reflect misinterpretation of my original claims.
The goal of this study was to determine if auditory cues are important in maternal recognition by domestic cattle calves, Bos taurus. Cows and their calves were separated and the vocalizations of the mothers were recorded. During experimental playbacks in a test enclosure, each calf (n = 9) was given a choice between a tape-recorded vocalization of its mother and that of a strange mother. Calves significantly preferred their own mother's vocalization as compared to the vocalization of the unfamiliar mother. Calves spent significantly more time near the speaker that played their own mother's call, and approached significantly closer to their mother's speaker. These results demonstrate that 3–5-wk-old calves can recognize their mothers by auditory cues alone. Visual inspection of audiospectrograms of the cows' vocalizations suggests that there are individual differences among cows.
All species in the genus Macaca produce a set of harmonically rich vocalizations known as “coos”. Extensive acoustic variation occurs within this call type, a large proportion of which is thought to be associated with different social contexts such as mother-infant separation and the discovery of food. Prior studies of these calls have not taken into account the potential contributions of individual differences and changes in emotional or motivational state. To understand the function of a call and the perceptual salience of different acoustic features, however, it is important to determine the different sources of acoustic variation. I present data on the rhesus macaques' (M. mulatta) coo vocalization and attempt to establish some of the causes of acoustic variation. A large proportion of the variation observed was due to differences between individuals and to putative changes in arousal, not to differences in social context. Specifically, results from a discriminant-function analysis indicated that coo exemplars were accurately assigned to the appropriate individual, but vocal “signatures” were more variable in some contexts than in others. Moreover, vocal signatures may not always be reliable cues to caller identity because closely related individuals sound alike. Rhesus macaque coos evidently provide sufficient acoustic information for individual recognition and possibly kin recognition, but are unlikely to provide sufficient information about an external referent.
Many territorial birds are capable of recognising neighbours from their songs. In this paper we investigate the timing of learning of neighbours' songs for recognition. This is the first time that the timing of discrimination learning has been studied explicitly by experiment in the field. We show that discrimination learning is not limited to early life and contrast this with the timing of song learning for performance. We also show that the ability to recognise new neighbours is inversely related to the number and similarity of neighbour's songs which have previously been experienced. This suggests pro-active memory interference and provides the first field evidence for memory constraints on discrimination.
Red squirrels defend exclusive, individual territories year round, 20% to 50% of females do not breed in any given year, and breeding females raise juveniles on their territories. Breeding is asynchronous, and the offspring of early-breeding females are more likely to hold an independently won territory than are late-born offspring. Based on the asymmetric war of attrition, we made the following predictions: (1) squirrels would respond more intensely to the calls of unfamiliar individuals than to the calls of neighbors; (2) breeding females would respond more intensely to unknown calls than would non-breeding females or males; (3) early-breeding females would respond more intensely than would late-breeding females to unknown calls; and (4) all classes of squirrels would respond similarly to the calls of neighbors. Playback experiments supported the predictions. Alternative hypotheses of kin selection, risk of infanticide, and seasonal difference in intruder pressure could not explain the results.
Several types of low frequency calls made by African elephants, Loxodonta africana, and the contexts in which they occurred are described. These calls had fundamental frequencies ranging from 14–35 Hz and sound pressure levels as high as 1033dB (re 20 Pa) at 5 m from the source. Very low frequency sounds are subject to very little environmental attenuation, suggesting that sounds at the frequencies and sound pressure levels measured from elephants may be audible to conspecifics several km away. Long-term records on the behavior of elephants and on the contexts of specific call types suggest that elephants make use of infrasound in the spatial coordination of groups and as they search for mates.
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SYNOPSIS. The ability of animals to recognize and classify others reflects the selective pressures acting on individuals within a particular social framework. Data on recognition therefore allow us to consider social structure from the animal's point of view. Here we review data on recognition within groups of free-ranging vervet monkeys, and present evidence of recognition across groups. Within groups, experiments suggest that animals may proceed beyond simple discriminations of kin and non-kin to create a taxonomy in which group members are both distinguished as individuals and grouped into higher order units, apparently on the basis of matrilineal kinship. Across groups, observation indicates that male transfer is non-random, and that the exchange of males between groups is correlated with reduced aggression. Playback experiments demonstrate that monkeys associate the vocalizations of particular individuals with particular groups. We conclude that the social organization of vervet monkeys is best regarded as a “community” of groups, within which individuals recognize each other and share a high degree of genetic relatedness despite the maintenance of otherwise discrete social units.
Evidence for long-term chemical memory in elephants
- Rasmussen
Rasmussen, L. E. L. 1995. Evidence for long-term chemical memory in elephants. Chemical Senses, 20, 237–237.