IUCN/SSC Otter Specialist Group Bulletin
©IUCN/SCC Otter Specialist Group
Volume 39 Issue 3 (September 2022)
Abstracts
Group Dynamics and Habitat Use of the Giant Otter, Pteronura brasiliensis (Zimmermann, 1780), in Seasonally Flooded Forest in the Araguaia River, Central Brazil: A 10-Years Study
Pages 125 - 146 (Article)
Benaya Leles, George Georgiadis, Nils Kaczmarek, Reuber Brandão, And Silvana Campello
We carried out monthly surveys of the giant otter population between 2010 and 2020 in a study area comprised of 1,500 hectares of igapó flooded forest with oxbow lakes in the Cantão region of central Brazil. We recorded 16-32 resident adults in the study area each year, distributed in 4-8 groups. Resident groups exhibited extensive home range overlap, with each group using several lakes and larger lakes used in rotation by up to six groups. Dens and campsites were also shared by multiple groups, but lakes were used by only one group at a time, and encounters between groups were very rare. Twenty-four adult otters were observed to join an existing group. Some individuals changed groups multiple times. Resident adult turnover was high. Each year an average of 36% of resident adults were new immigrants, and 72% of groups left the area within two years. Resident groups had, on average, one litter every three years, and annual cub production showed high variability and a negative correlation to the number of new immigrants in the area. No pairs of giant otters reproduced successfully during the study. Groups of three otters formed through the recruitment of an adult individual by an existing pair and reproduced as successfully as larger groups. Group dynamics and territorial behavior in the Cantão flooded forest ecosystem, where optimal giant otter habitat is continuous in all directions, were found to be different from that reported in areas composed of patchy (isolated oxbow lakes) or linear (rivers) habitat. This suggests that giant otter social and territorial behavior is plastic and adapts to the spatial characteristics of the habitat.
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Giant Otters (Pteronura brasiliensis) at the Aquidauana River
Pages 147 - 1579 (Article)
Oldemar Carvalho Junior, Alesandra Bez Birolo, Anwar Sabbagh, and Andreoara Schmidt
We carried out monthly surveys of the giant otter population between 2010 and 2020 in a study area comprised of 1,500 hectares of igapó flooded forest with oxbow lakes in the Cantão region of central Brazil. We recorded 16-32 resident adults in the study area each year, distributed in 4-8 groups. Resident groups exhibited extensive home range overlap, with each group using several lakes and larger lakes used in rotation by up to six groups. Dens and campsites were also shared by multiple groups, but lakes were used by only one group at a time, and encounters between groups were very rare. Twenty-four adult otters were observed to join an existing group. Some individuals changed groups multiple times. Resident adult turnover was high. Each year an average of 36% of resident adults were new immigrants, and 72% of groups left the area within two years. Resident groups had, on average, one litter every three years, and annual cub production showed high variability and a negative correlation to the number of new immigrants in the area. No pairs of giant otters reproduced successfully during the study. Groups of three otters formed through the recruitment of an adult individual by an existing pair and reproduced as successfully as larger groups. Group dynamics and territorial behavior in the Cantão flooded forest ecosystem, where optimal giant otter habitat is continuous in all directions, were found to be different from that reported in areas composed of patchy (isolated oxbow lakes) or linear (rivers) habitat. This suggests that giant otter social and territorial behavior is plastic and adapts to the spatial characteristics of the habitat.
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What does a Discovery tell Us? Camera-Trapping Insight into the Asian Small-Clawed Otter in North-Eastern Bangladesh
Pages 158 - 170 (Article)
Muntasir Akash, Sultan Ahmed, Joyanto Biswas, Mohammad Samiul Alam, Tania Zakir, S M Shafi, Azizul Islam Barkat, Md Tazul Islam, Haris Debbarma, Khurshed Alom, Chonchol Guala
For three of the four Oriental otters that live in Bangladesh, as of early 2022, four pertinent peer-reviewed studies were conducted in the country. The distribution of the country’s otters, because of the dearth of empirical evidence, is made of guesswork and yet to be scientifically understood. Subsequently, eastern forests although a part of the globally recognized range of the small-clawed otter (Aonyx cinereus) are not accredited in Bangladesh for the species and are not receiving any conservation investment. This study, for the first time, provided evidence of the relict populations of small-clawed otters in eastern Bangladesh. A survey on terrestrial carnivore mammals was carried out between January and October 2021 in four north-eastern forest reserves that found the species in three reserves, with 132 notionally independent events from a sampling effort of 3629 camera-trap nights. The activity rhythm of nocturnal–crepuscular otters leaned more towards dawn. The work highlights (i) the potential of the small-clawed otter as an umbrella species for the traditionally ignored, trans-border riparian mixed-evergreen forests of north-eastern Bangladesh; (ii) a great inconsistency between sources concerning its distribution in the country; (iii) the necessities to investigate the lack of this survey’s records of smooth-coated otter (Lutrogale perspicillata) and Eurasian otter (Lutra lutra, no evidence in Bangladesh for 30 years) although the surveyed forest reserves are widely noted for both species; and (iv) the stark absence of any recent information on otter status in the adjacent Indian states (Meghalaya, Tripura, Mizoram, and southern Assam) that, together with eastern Bangladesh, belong to an ecologically uncharted territory and form the western limit of the Indo-Burma Biodiversity Hotspot.
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Distribution of the Asian Small-Clawed Otter (Aonyx cinereus) in Chhattisgarh, India
Pages 171 - 178 (Report)
Ravi Naidu, Krunal Trivedi, Ameet Mandavia, Saurabh Singh, A.M.K. Bharos, Shivbhadrasinh Jadeja, and Nileshkumar Kshirsagar
The Asian small-clawed otter (Aonyx cinereus) is the smallest among 13 species of otters. Very little information is available about the status and distribution of Asian small-clawed otters in Chhattisgarh. The current study reports the presence of otters at 20 different sites in 5 districts of Chhattisgarh. To confirm the presence of the otters in this region, we used camera traps, sign surveys, and direct sightings. Threats like habitat destruction, sand mining, and extensive fishing were identified. Systematic otter surveys are needed in this region to make an accurate population assessment and to create an otter-specific conservation plan.
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On the Current Occurrence of the Neotropical Otter (Lontra longicaudis OLFERS, 1818) in a Degraded River after a Dam Collapse, Southeast Brazil
Pages 179 - 184 (Report)
Andre M. Lanna, Fabiola Keesen, and Carlos E.V. Grelle
The Neotropical otter (Lontra longicaudis) is a semi-aquatic predator that occurs in a wide geographic distribution in the Neotropical region, and can be used as indicator of ecosystem health. In January 2019, the Paraopeba River, which has historically been affected by anthropic activities, was impacted by the B1 iron ore tailings’ dam collapse. This might have caused severe negative impacts to the entire fauna of the region. We carried out an inventory along the Paraopeba River to assess the current occurrence of the Neotropical otter in such asystem. The results obtained indicate the occurrence of this species in the study region eight months after the damage, with records upstream and downstream of B1 dam.
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