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Sociality of species (occurrence > 40% of mixed flocks; 144 hours of survey). White column: solitary individuals or pure groups; gray: birds within mixed flocks. In brackets the sample size for each species.
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In bird mixed flocks, a prominent species, the so-called nuclear species, improves the cohesion and maintenance of the flocks, while other less conspicuous species are assumed as satellite. In this study we described the composition, as well as examined the existence of both nuclear and satellite species in mixed flocks of a savanna in the Pantanal...
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Risk effects, or the costs of antipredator behavior, can comprise a large proportion of the total effect of predators on their prey. While empirical studies are accumulating to demonstrate the importance of risk effects, there is no general theory that predicts the relative importance of risk effects and direct predation. Working toward this genera...
Anti-predator signaling is highly variable with numerous examples of species employing cryptic coloration to avoid detection or conspicuous coloration (often coupled with a secondary defense) to ensure detection and recollection. While the ends of this spectrum are clear in their function, how species use intermediate signals is less clear. Austral...
Predation risk" and "fear" are concepts well established in animal behavior literature. We expand these concepts to develop the model of the "landscape of fear". The landscape of fear represents relative levels of predation risk as peaks and valleys that reflect the level of fear of predation a prey experiences in different parts of its area of use...
Movement in animal groups is highly varied and ranges from seemingly disordered motion in swarms to coordinated aligned motion
in flocks and schools. These social interactions are often thought to reduce risk from predators, despite a lack of direct
evidence. We investigated risk-related selection for collective motion by allowing real predators (b...
Adaptive responses to predation are generally studied assuming only one predator type exists, but most prey species are depredated by multiple types. When multiple types occur, the optimal antipredator response level may be determined solely by the probability of attack by the relevant predator: "specific responsiveness." Conversely, an increase in...
Citations
... A Brazilian Ruby (Clytolaema rubricauda) male mobbed too closely an apparently oblivious owlet perched by the feeder and was snatched in mid-air by a sudden movement of the predator. Hummingbirds are readily attracted to a perched Ferruginous Pygmy Owl or to the playback of its vocalisation (Sick 1997, Motta-Junior 2007, Amaral & Ragusa-Netto 2008, Cunha & Vasconcelos 2009). Thus, it is possible that part of successful hunting on hummingbirds by pygmy owls results from mobbing episodes (see Sick 1997). ...
Pygmy owls of the genus Glaucidium prey on large insect and small vertebrates, mostly birds. Among the birds preyed on by pygmy owls are hummingbirds, caught mostly while mobbing these owlets or when still at nestling stage. I report here on the Ferruginous Pygmy Owl (Glaucidium brasilianum) snatching flower-visiting hummingbirds in an orchard at a farm in southwestern Brazil. I recorded one Glittering-bellied Emerald (Chlorostilbon lucidus) and three Gilded Hummingbirds
(Hylocharis chrysura) preyed on by this owlet on three consecutive days. The large concentration of flowers and, consequently, of hummingbirds in the orchard likely contributed to the hunting success of the owlet on such fleeting and quickly moving prey. The role this pygmy owl plays on predation of adult hummingbirds in the Neotropics merits closer consideration.
... Neotropical MSFs in forest are composed primarily of pairs of most species (Munn 1985), but in savanna flocks on the Pantanal the Suiriri Flycatcher Suiriri suiriri (Family Tyrannidae), which forms small groups, served as a nuclear species (Amaral and Ragusa-Netto 2008). The situation may be different in the Indo-Malayan and Australasian regions. ...
Mixed-species flocks of foraging insectivorous birds are found worldwide and have been best studied in the Neotropical region. A survey of the published literature reveals that mixed-species flocks (often termed ‘bird parties’) comprised of 2–30 species and sometimes >70 individual birds are regularly encountered in forest and woodland habitats throughout the Afrotropical region. On mainland Africa, >600 species representing 59 bird families have been reported in such flocks, and for at least 300 species foraging in such flocks may constitute an important part of their feeding activity. In Madagascar, >60 species of 19 families have been recorded in mixed-species flocks, with more than 40 species frequent participants. These foraging parties are dominated by gleaning and sallying insectivorous birds, with other feeding guilds represented by fewer species and individuals. The main hypotheses to explain why birds participate in such flocks emphasise protection from predators while searching for food, and increased foraging efficiency through the disturbance of insects caused by the different foraging activities of flock members. Certain key species may be responsible for the initial formation of the flock. Mixed-species flocks are regarded as particularly vulnerable to disruption by anthropogenic habitat changes, especially to forests, and are thus of special conservation concern. In the Afrotropics, these proposals remain working hypotheses since we currently lack data for a full assessment of the ecological role of mixed-species flocks and their importance in the life history of the participating species.
... This is interesting as so far the Long-tailed finch was more seen as a superior competitor with respect to nest holes [31]. In contrast, around waterholes Long-tailed finches may act as a nuclear species [46] for Gouldian finches. Why they prefer this species above others is unknown but may be explained with their co-occurrence across the species' range and their similar ecological requirements, although the Long-tailed finch is much more a generalist than the Gouldian finch [31]. ...
Colour polymorphism is a widespread phenomenon and often encompasses different behavioural traits and strategies. More recently, it has been shown that morphs can also signal consistent individual differences (personality). An example are Gouldian finches that show discrete head colour morphs in the same population with red-headed birds being more aggressive but less risk-taking and explorative than black-headed birds in the lab. The current study aimed to investigate the link between head colour and behavioural traits in a naturally risky situation in the wild by recording the order of descent at waterholes in relation to hypotheses considering conspicuousness, dominance relationships and experience. Other bird species at the waterholes were also included in the study. Adult Gouldian finches generally preceded juveniles and among the adults the least conspicuous black-headed females descended first to the waterhole. Overall, females descended before the males though this pattern disappeared later in the season likely due to family groups breaking up and releasing males from attending to the juveniles. Finally, Gouldian finches almost always followed other species, particularly Long-tailed finches, to the ground rather than taking the lead. A two-level process of decision-making seems to explain the responses best: on the first level, experience separates adults from juveniles with adults preceding juveniles and on the second level, conspicuousness acts as a factor among the adults with the least conspicuous category taking the lead. Future studies should directly test the link between head colour and personality in the wild, look more into seasonal effects and investigate whether Gouldian finches use Long-tailed finches as an indicator of safety.
... Nevertheless, studies are not equally distributed throughout the globe. Historically, much more attention has been given to forested habitats, such as temperate broadleaf forests and to tropical rainforests, whereas fewer studies have been conducted in other environments, such as savannah and dry shrublands (Alves & Cavalcanti 1996, Jones & Bock 2003, Amaral & Ragusa-Netto 2008, Zarco & Cueto 2017. ...
... There are numerous studies that evaluate patterns in structure, composition and social role of the species that participate in flocks in the Neotropics (Munn & Terborgh 1979, King & Rappole 2000, Tubelis 2007, Amaral & Ragusa-Netto 2008, Knowlton & Graham 2011, Fanjul & Echevarria 2015, but virtually none of them investigates latitudinal effects. The subtropical mountain forest of the Yungas in Argentina is distributed from northern Salta (limit with Bolivia) to the north of Catamarca province encompassing approximately 700 km of extension. ...
Mixed-species flocks of birds have been studied for more than a century, but investigation efforts are historically
unbalanced towards certain types of habitats, such as woodlands and lowland forests. Here we provide a first glance of bird flocks'
patterns across different gradients in recent studies conducted within the Neotropics. We summarize a symposium where a series of
independent studies that approached the topic, some of them making use of techniques that were seldom applied in previous decades
in Neotropical systems. We discuss bird flocks' patterns across a latitudinal gradient, social network patterns in bird flocks' across
elevational gradients in local and regional scale, and, finally, patterns of flocking response to different levels of human disturbance.
Altogether, these studies offer a larger and diverse panorama of possible patterns of response and diversity of mixed-species flocks
of birds in the Neotropical region, and provide a rich ground where future studies with bird flocks in the Neotropics may rely on..
... Bird species that promote the formation and maintenance of mixed flocks are often termed ''nuclear species,'' and associating species are termed ''satellite species'' (Moynihan 1962). Nuclear species have conspicuous calls, movement, and coloration, and effective antipredator detection (Amaral and Ragusa-Netto 2008). The nuclear species concept is also relevant for primatology, and at Taï Forest, Côte d'Ivoire the vividly colored and very vocal Diana monkey (Cercopithecus diana) has been called a nuclear species for red colobus monkeys (Procolobus badius), Campbell's monkey (C. ...
... I then provided data on predator presence as well as responses to predators and other stimuli to evaluate potential antipredator benefits of association with C. diana. I predicted that C. diana would most often be the first caller to harmful stimuli, as found in previous studies of C. diana and other nuclear species (Bshary and Noë 1997a;Amaral and Ragusa-Netto 2008). ...
Polyspecific associations (PSA) are common in many African primate communities, including the diurnal primates at Taï Forest, Côte d'Ivoire. In this paper I use data on the PSA of two forest guenons, Campbell's (Cercopithecus campbelli) and lesser spot-nosed monkeys (C. petaurista), with Diana monkeys (C. diana) and other primates to clarify interspecific relationships during 17 months including a 3-month low-fruit period. I analyzed association in relation to fruit availability and measured forest strata use for C. campbelli and C. petaurista when alone and in associations with and without C. diana. I also measured predator risk and reactions to potential predators. C. campbelli and C. petaurista had high association rates with C. diana monkeys, and fruit availability did not influence association rates. C. campbelli and C. petaurista used higher strata when in association with C. diana than when alone, but they used even higher strata when associated with other primates without C. diana. This suggested that C. diana competitively exclude C. campbelli and C. petaurista from higher strata. There were relatively large numbers of potential predators, and C. diana were usually the first callers to threatening stimuli, suggesting that antipredator benefits of association with C. diana outweighed the competitive costs. C. campbelli spent more time in association with C. diana than C. petaurista did and appeared to be more reliant on C. diana for antipredator benefits. C. petaurista were less reliant on C. diana because of a cryptic strategy and may have associated less in some months because of high chimpanzee (Pan troglodytes) presence.
Abstract. Several phytogeographic regions (Cerrado, Pantanal, Atlantic Forest, Gran Chaco, and Chiquitano Dry Forests) converge in the state of Mato Grosso do Sul, Brazil, and influence regional biodiversity. Despite a list of birds in the state of Mato Grosso do Sul being published by Nunes et al. (2017), it is necessary to update and critically review avifauna records. In this study, we gathered the results of several records obtained from species lists and online data platforms of the 336 sites in this state over the last decades and grouped them into Main (Primary and Secondary) and Tertiary Lists. The avifauna of Mato Grosso do Sul is composed of 678 species, of which 643 (95%) have records proving their occurrence (Primary List), whereas 34 still lack documentation (Secondary List). The number of related species for Mato Grosso do Sul represents 34% of the Brazilian avifauna. Some species stand out for their unique occurrence in Mato Grosso do Sul, such as Melanerpes cactorum, Celeus lugubris, Phaethornis subochraceus, and Cantorchilus guarayanus, reflecting the influence of different phytogeographic regions of the Chaco and Chiquitano Dry Forests. Migrants represent 20% of the bird community occurring in the state, of which 93 species correspond to migrants from various regions of South America (south and west) and 40 to boreal migrants. Thirty-three species perform nomadic movements across the Pantanal Plain and other regions of the state. Thirty-one species are included in some conservation-threatened categories of global and/or national endangered species lists. Other 30 species are included in the near-threatened category at the global level and 23 at the national level. In addition, species typical of dry forests (in Serra da Bodoquena and Urucum Massif) and those from the Atlantic Forest in the south of the state deserve attention due to their restricted distribution and the high anthropogenic pressure on their habitat.
Mixed-species flocks (MSF) are associations of different species formed as a strategy to increase the efficiency of foraging and to reduce the risk of predation. The aim of the present study was to determine the variation of the composition and structure of the MSF, along a latitudinal gradient in the subtropical mountain forest of the Yungas of Argentina. Eight sampling sites were studied along the 700 km of distri-bution of the Yungas in Argentina. Ten transects at each site were established and were visited from June to September between 2006 and 2009. It was determined the richness and abundance of the MSF. 325 MSF, with a total of 72 participating spe-cies and an abundance of 2480 individuals were observed. Seventeen families were represented, 15 of the order Passeriformes and two non-passerines (Trochilidae and Picidae). Tyrannidae (12 species), Furnariidae (10 species) and Thraupidae (nine species) were the major families. Twelve species were omnipresent in the eight study sites, being Syndactyla rufosuperciliata, Phylloscartes ventralis, Chlorospingus flavopec-tus and Myioborus brunniceps the species that had the highest values of occurrence. Although multivariate statistical analyzes, indicated that the latitudinal gradient would have no direct influence on the structural characteristics (number of flocks, number of species and individuals involved) of the MSF, the composition of species varied in association with latitude. Some causes associated with the gradient, such as local climate, vegetation characteristics and food availability, could influence the results obtained.
The Pantanal floodplains of Brazil are a region of rich biodiversity. To date, the true richness of the Pantanal avifauna has not been explored satisfactorily caused by a lack of studies in the region and, especially, by the divergence of opinion among the works published by various authors on the many species found in the region. This is due to the lack of criteria in examining records, both with regard to the reliability of the identifications and in the precise geographical allocation. Therefore, in the study, we collage findings from various studies and records created by us in the last few decades from 199 distinct locations to produce a list of birds in the Pantanal floodplains. We grouped the results into three lists: primary, secondary, and tertiary. We found that the avifauna of the Pantanal floodplain is composed of a total of 617 species, of which 571 (92%) have supporting records of occurrence (primary list) and 46 still lack documentation (secondary list). The number of species listed here for the Pantanal floodplain represents 32% of all avifauna known to the Brazilian territory. This reflects the importance of the biome, as part of the national territory, for the maintenance of a meaningful avifaunistic richness. Migratory birds (n = 183), notably northern ones (n = 43), are among the main players involved in ecological processes of nutrient cycling and dispersion of ARTICLE important pathogens between the two continents. With regard to conservation, 25 species are included in some category of threat in the lists of threatened species with global extinction. We hope that our list will help future researchers a more definitive approach when researching the avian fauna in this bountiful region.
Mixed bird flocks are groups of individuals from different species that travel and forage together. Such groups are common in several bird communities around the world. We present species composition and activity patterns of mixed bird flocks in a region of the Central Andes of Colombia. We compared the number of species per flock, as well as the number of flocks among 3 different habitats. We tested hypotheses concerning the flocks daily activity and the co-occurrences of species within them. We recorded 75 species, and the species number per flock varied from 4 to 21. Our data suggest that habitat affects the number of flocks but not their species number, and that the activity of flocks is similar throughout the day. In addition, the association of birds in flocks is affected by interspecific facilitation, with some species co-occurrences found more times than expected by chance. We hypothesize that some tanager species could have a role in flock cohesion. We witnessed 2 predator attacks upon flocks, a number of agonistic interactions among flock members, and squirrels following bird flocks. Our results meet some general patterns described for mixed bird flocks.
Populations of grassland birds are declining in Brazil due to profound alterations to grassland habitats. In this paper, we present recent records and range extensions for 12 threatened or little known Brazilian grassland species: Ocellated Crake Micropygia schomburgkii, Sickle-winged Nightjar Eleothreptus anomalus, Campo Miner Geositta poeciloptera, Rufous-sided Pygmy-tyrant Euscarthmus rufomarginatus, Sharp-tailed Grass-tyrant Culicivora caudacuta, Cock-tailed Tyrant Alectrurus tricolor, Cinereous Warbling-finch Poospiza cinerea, Black-masked Finch Coryphaspiza melanotis, Tawny-bellied Seedeater Sporophila hypoxantha, Marsh Seedeater S. palustris, Chestnut Seedeater S. cinnamomea and Black-bellied Seedeater S. melanogaster. We also comment on the biogeography and conservation of these species.
