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Mating herd of Amazonian manatees (Trichechus inunguis) filmed on Bispo Beach, Mosqueiro Island, near Belém, Pará, Brazil, 31st October 2021. Note the so-called 'manatee ball', as usually reported by fishers and locals for mating groups of manatees. Images captured from popular videos.
Source publication
The West Indian manatee Trichechus manatus Linnaeus, 1758 and the Amazonian manatee T. inunguis (Natterer, 1883) occur in the Marajó Bay area and in the inlets and channels near Belém. The Amazon Aquatic Mammal Study Group (GEMAM) coordinates a collaborative network for trapped and rescued manatees along the coast of the state of Pará and in the in...
Context in source publication
Context 1
... videos, widely publicized in the local and national media, clearly suggest that mating took place, as one large manatee held the alleged female for more than 2 minutes (Figure 3 Hartman, 1979). This is in agreement with the reported behavior known as 'manatee riding' by residents of the Amazon basin (Pereira, 1944). ...
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Vocal activity and signal characteristics of mammals are driven by several factors that result in both stability and plasticity over multiple time scales. All three extant species of manatee communicate with several calls that are especially important for maintaining contact between cows and calves. Determining if calf calls differ across manatee s...
Citations
... The reports of this vigorous and promiscuous behavior are also present in interviews of local communities (Calvimontes & Marmontel, 2006). Recently, direct observations of Amazonian manatee mating herds were reported in Brazil (middle-Solimões River and Pará River estuary) and Ecuador (Reserva de Producción de Fauna Cuyabeno) Emin-Lima et al., 2021). All those observations reported an active interaction among males disputing for a position next to the receptive female. ...
The last relevant work that reviewed the biological and conservation aspects of the Amazonian manatee (Trichechus inunguis) was published almost 30 years ago. In these three decades, scientific knowledge about the species has advanced substantially. This review article updates knowledge about the various biological and conservation aspects of Amazonian manatee, summarizing the information present in the literature. Topics such as morphology, habitat, distribution, population aspects, food and feedings habits, reproduction, behavior, health, threats, status, and conservation efforts were addressed. The main actions already carried out, as well as the future strategies needed for the conservation of the Amazonian manatee, are also highlighted.
The analysis of chromosome structure and variation can provide important information for the management and reproduction of threatened species, in situations where molecular results could not solve issues concerning genetic risks and reproductive problems. In this regard, some molecular studies have proposed the occurrence of hybrids between the two species of manatees found in South America (Trichechus manatus and Trichechus inunguis), in the area surrounding the Amazon delta, where these species are found in sympatry. Despite the controversial results obtained from different molecular approaches, and the obvious chromosomal differences that could help identify possible hybrids (2n = 48 in T. manatus and 2n = 52 in T. inunguis), only recently the occurrence of hybridization in nature between these two species has been unequivocally confirmed by a study based on cytogenetic analyses. In this sense, we present a review focusing on the karyotypic information from South American manatees, and the importance of chromosomal data on the conservation of these species. We demonstrate that cytogenetic studies could also indicate the analyzed hybrids did not show an F1 karyotype, bringing important information concerning the viability of hybrids. Hence, because chromosomal analyses allow an undeniable identification of hybrids between species with distinct karyotypes, cytogenetic analysis should be considered an essential part in the management of captive and threatened mammals, reinforcing the importance of comparative cytogenetics in the conservation genomics era.KeywordsComparative cytogeneticsKaryotypeHybridizationReproductive barrierThreatened mammals
