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Abstract:Circadian use of time is an important, but often neglected, part of an animal's niche. We compared the activity patterns of the Neotropical otter Lontra longicaudis in two different areas in Brazil using camera traps placed at the entrance of holts. We obtained 58 independent photos in the Atlantic Forest (273 camera trap-days) and 46 photos in Pantanal (300 camera trap-days). We observed different kernel density probabilities on these two areas (45.6% and 14.1% overlap between the 95% and 50% density isopleths respectively). We observed the plasticity in Neotropical otter activity behaviour with different activity patterns in the two areas. In the Pantanal, the Neotropical otter selected daylight (Ivlev = 0.23) and avoided night (Ivlev = −0.44), while in the Atlantic Forest it selected dawn (Ivlev = 0.24) and night (Ivlev = 0.14), avoiding daylight (Ivlev = −0.33). We believe that this pattern can be due to human activity or shifts in prey activity.

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1. The Neotropical otter Lontra longicaudis is a widespread semiaquatic carnivore living in a wide variety of environments in both fresh-water and salt-water ecosystems. We summarise the current knowledge on distribution, ecology, behaviour, evolution and conservation status of the species, and highlight the main threats that have been affecting it as well as priority actions for securing its survival. 2. The current geographical range of Lontra longicaudis is discussed, as well as several efforts that have been made to update knowledge of the range. Throughout its known distribution area, the Neotropical otter has high genetic diversity, and recent molecular research suggests that variations in genetic diversity are related to geography. Taxonomic issues regarding the existence of subspecies persist, mainly due to limited sampling in key portions of the species' range. 3. Although the Neotropical otter is widely distributed in Latin America and has flexible behaviour, it is subjected to a variety of threats, which lead this otter to be officially considered Threatened in several countries within its geographical range. 4. The species still faces an uncertain future due to the impact of human activities, thus justifying its classification as Near Threatened in the International Union for Conservation of Nature's Red List. The real level of human-otter conflicts and the impact of modified environments on Neotropical otter populations are still unclear, and must be a priority focus of future studies. 5. There is an urgent need to increase our knowledge on aspects of the Neotropical otter's biology, such as reproduction, generation time, behaviour, physiology, distribution limits, sanitary aspects, evolution and taxonomy. Understanding these topics is vital to ensure the long-term survival of the species, both at the local and at the regional scale, as well as to provide the basis for environmental education actions involving local riverside human communities.

Understanding a species' occurrence requirements is essential for its conservation, and species distribution models (SDMs) are a powerful tool for this purpose. Here we estimated a SDM based on actual distribution information, in relation to climatic, hydrological, human population, and vegetation data sets, to understand the ecological requirements and geographic distribution of the Neotropical otter Lontra longicaudis, a species whose habitat requirements and conservation needs are mostly unknown. Using MaxEnt, we defined its potential distribution and most suitable areas to indicate priority areas for research and to analyze the efficiency of Protected Areas (PAs). Our findings suggest that the range of Neotropical otters could extend beyond their present estimated distribution, adding new areas in northeastern Brazil, Andean region, west Ecuador, Venezuela, Peru, Mexico, and Argentina, with higher suitability in rain forests (especially Atlantic and Amazon Forests). We also found that PAs are the most suitable areas for otter distribution. Although better than non-protected areas, PAs are close to the median of the suitability values, indicating that they still can be improved to conserve otters. Annual temperature and human population density explained most data variance in our model. We suggest the change of the actual status of Neotropical otter to Least Concern or Near Threatened categories. We recommend verifying the possible sympatry with other otters, and demonstrate that rudimentary and/or occasional recent data of occurrence can also be used in SDMs and contribute to species conservation.Keywords: distribution range, Neotropical otter, niche modeling, reserve design, suitability Resumo Compreender os requisitos para a ocorrência de uma espécie é fundamental para sua conservação, e os modelos de distribuição de espécies (SDM) são uma ferramenta poderosa para essa finalidade. Aqui nós estimamos um SDM a partir de informações reais de distribuição, em relação a conjuntos de dados climáticos, hidrológicos, de população humana e de vegetação para entender as exigências ecológicas e a distribuição geográfica da lontra Neotropical Lontra longicaudis, espécie cujos requisitos de habitat e necessidades para a sua conservação são praticamente desconhecidos. Usando MaxEnt, definimos sua distribuição potencial e as áreas mais adequadas para a espécie a fim de indicar áreas prioritárias para pesquisa e analisar a eficácia das áreas protegidas (APs). Nossos resultados indicam que a distribuição da lontra neotropical poderia se estender além de sua distribuição atual estimada, adicionando novas áreas no nordeste do Brasil, na região andina, no oeste do Equador, na Venezuela, no Peru, no México e na Argentina, com maior adequabilidade em florestas tropicais (especialmente Mata Atlântica e Floresta Amazônica). Descobrimos também que APs são as áreas mais adequadas para a distribuição de lontra. Porém, embora sejam mais adequadas do que áreas não protegidas, as APs estão perto da mediana dos valores de adequa...

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The diet of the Neotropical otter Lontra longicaudis (Olfers, 1818) is one of the best known aspects of its biology throughout its distribution range. However, most dietary studies have been undertaken during short time periods, making it difficult to identify temporal patterns in the feeding behavior of the species. The present study aimed to describe the diet of L. longicaudis in the lower region of the Mambucaba Catchment, state of Rio de Janeiro, Brazil, during a three year period, based on analyses of spraints (feces). The results show fish as the main prey item (frequency of occurrence, FO = 85.78%), as already described in previous studies. Crustaceans were the second main prey (FO = 70.67%), occurring in the spraints during the whole year, however presenting a higher frequency of occurrence than fish in samples collected during some months. Anurans were the third most important prey item (FO = 9.56%) and mammals, birds and reptiles were preyed upon only rarely (less than 4%). Fish and crustaceans were present in the diet of the species throughout the year and frogs were important mostly from June to August (dry season). This higher rate of predation on amphibians during the drier months was probably related to the decrease of the main prey

We examined the evidence supporting the hypothesis that jaguars (Panthera onca) have morphological and behavioural adaptations to facilitate reptile predation. Jaguars' head and bite features show adaptations to durophagy (consumption of hard-integumented prey) that are very unusual within the genus Panthera. These include: thick canines, well-developed head muscles and a fatal bite directed to braincase or nape. These characteristics have been previously considered an adaptation for the consumption of reptilian prey, whose thick integument poses a challenge to predation. Although causation of any trait as result of natural selection is hard to demonstrate with ecological evidence, its consequences can be suggested and predictions made. Here, through a review of the literature on jaguar predatory habits, we tallied the evidence for saurophagy against environmental characteristics correlated with jaguar predation on reptiles. We offer a new explanation for the presence of those traits, based on the selection patterns, prey abundances and main predation habits over the geographic range of the jaguar. We believe that these features allow jaguars to overcome dangerous and/or armoured prey by dispatching them rapidly through a bite to the head or nape. Reptile consumption is restricted to areas of high reptile abundance while dangerous or armoured prey is consistently preyed upon throughout the jaguar's distribution, and selected even when their abundance is low. This questions the validity of the saurophagy hypothesis. We believe that these results are relevant to jaguar conservation and management, because some of the main prey species are severely threatened over their range, and because threatened reptiles are also consumed as prey. ARTICLE HISTORY