IUCN/SSC Otter Specialist Group Bulletin
©IUCN/SCC Otter Specialist Group
Volume 38 Issue 4 (August 2021)
Abstracts
Status of Conservation of Lontra longicaudis (Olfers, 1818) (Carnivora: Mustelidae) on Santa Catarina Island
Pages 186 - 201 (Article)
Oldemar Carvalho Junior, Procássia Maria L. Barbosa, and Alesandra Bez Birolo
Neotropical otters (Lontra longicaudis) are semi-aquatic mammals classified as “Near threatened” by the International Union for Conservation of Nature (IUCN), facing various threats against their survival, such as habitat fragmentation, water pollution, conflicts with fishermen, or attacks by dogs. A total of 9.531 scats were collected monthly over nine years, covering 14 years, from 2003 to 2017, in six different areas of study in Santa Catarina Island, Brazil. Frequency analysis through non-parametrical statistical tests and a polynomial regression model was applied. A linear model was also used following criteria and standards defined by the IUCN. Both methods were in agreement, showing a significant decrease in the number of Neotropical otter’s feces over this period. Because the modifications of the environment were constant during the last 14 years, the criterion to be adopted, according to the IUCN Red List, is A2. Therefore, the average reduction in the number of otter droppings over the past 14 years, or three generations, suggests that the population is critically endangered (CR).
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Dietary Adaptability of the Giant Otter, Pteronura brasiliensis (Mammalia: Mustelidae), in two Floodplain Systems in the Pantanal Wetland, Mato Grosso State, Brazil
Pages 202 - 216 (Article)
Júnio de Souza Damasceno, Júlio César Dalponte and Marília Couto Silva Shiraiwa
The giant otter, Pteronura brasiliensis, is an almost exclusively piscivorous mammal of the family Mustelidae, and an endangered species. The present study compared the diet of the giant otter in two floodplain systems of the Pantanal wetland, a permanent lake and a river branch, in the Poconé and Barão de Melgaço wetlands in the Brazilian state of Mato Grosso. Samples were collected during the dry seasons, with 43 spraints being collected from the lake and 31 from the river branch. The fish species present in the samples were identified based on the comparison of bone fragments found in the spraints with specimens of fish collected from the two floodplain systems. The diets were composed primarily of fish of the families Erythrinidae (94.6%), Cichlidae (91.9%), Pimelodidae (70.3%), Callichthyidae (63.5%), and Doradidae (60.8%). Catfish (Siluriformes) were more abundant in the samples from the lake, while characins (Characiformes) were well represented in the river branch. While the siluriform family Callichthyidae was a prominent component of the otter diet in both study areas, it has been rarely recorded in previous studies of P. brasiliensis in either the Amazon or Pantanal regions. Most of the fish recorded in the diet of the otter are not targeted by commercial fisheries in Mato Grosso. The varying characteristics of different aquatic systems are important determinants of the composition of the local fish fauna and are thus relevant to the feeding ecology of the giant otter in the Pantanal wetland.
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Habitat Use by the Eurasian Otter (Lutra lutra Linnaeus 1758) in a Non-Protected Area of Madhya Pradesh, India
Pages 217 - 227 (|Report)
Rahul Talegaonkar, Saloni Salaria, Dhirendra Bhargava, Jyotirmay Jena, Snehit Kumar Rahul, Aniruddha Dhamorikar, And Pranav Chanchani
Eurasian otter is one of the three otters found in India. In Central India, it was recently photo-captured in Balaghat district. We studied habitat use of Eurasian otters (Lutra lutra) by sampling 57 stream segments along the Wainganga River and Uskal stream in a reserve (non-protected) forest of Balaghat Forest Division in the months of March-April 2018 using sign surveys. We used an occupancy-based approach to determine the influence of habitat covariates on otter occupancy. Bank substrate had a significant positive impact on detection probability of otters. The probability of habitat use by otters strongly decreased as the bank width increased. Future studies should focus to better understand the impact of human activities on the distribution, demography, and behaviour of otters
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Feeding Strategies for Captive Asian Small-Clawed Otters (Aonyx cinereus, Illiger, 1815): What Works to reduce Repetitive Feeding Anticipatory Activity in the Cold Season?
Pages 228 - 248 (|Article)
Jacob Harrop and
Mirela Cuculescu-Santana
This case-study analysed the behaviour and enclosure use of a pair of Asian small-clawed otters to investigate the impact of changes in feeding strategy on repetitive behaviours associated with feeding anticipation, in the context of the influence of seasonal changes in temperature on these tropical mammals.
The otters displayed less swimming and resting, less sleeping and more begging, vocalisations and overall vigilance in winter compared to summer, suggesting more hunger due to increased energetic demands for thermoregulation.
The introduction of an additional mid-morning feed in winter without increasing the total amount of food per day was only partly effective on the targeted behaviours. The overall vigilance displays and vocalisations increased significantly, resting and sleeping decreased, but begging did not change compared to previous winter and summer values. Begging before the feed at 14:00 hours was less frequent, suggesting less hunger at this time, but increased to higher values later in the afternoon.
An increase in the total amount of food per day from 20% to 30% of otter body weight in January 2019, with return to 3 feeds/day, was more effective at reducing the targeted behaviours. There were decreases in overall vigilance displays and in the frequencies of begging and short calls and increases in play behaviours, social affiliative interactions and resting and sleeping, suggesting a reduction in levels of hunger and related stress.
This study emphasized the importance of considering how local climate affects enclosure conditions when assessing the nutritional, enrichment and climatisation needs of Asian small-clawed otters.
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Supplementary Material (PDF 404 KB)