Factors affecting the occurrence of smooth‐coated otter in aquatic systems of the Upper Gangetic Plains, India

Abstract

1. With the increasing human pressure on wildlife and its habitat, particularly in South and Southeast Asia, the population of the smooth-coated otter (Lutrogale perspicillata), a key carnivore of freshwater ecosystems, is rapidly declining. Reliable information on its abundance and other factors affecting its occurrence is lacking from many parts of its range, hindering development of conservation measures.2. In this paper the findings are presented on relative abundance and habitat parameters associated with the occurrence of the smooth-coated otter in the Corbett Tiger Reserve (CTR), India. Information on habitat structure, spraint (faeces) sites, and otter signs (e.g. footprints, spraints), were recorded in each 500 m section of five rivers in different seasons. The search covered 380, 100 m  15 m plots laid along the shoreline of the river banks. The importance of different habitat features influencing habitat selection was assessed using an ordination technique.3. In the CTR, the presence of otters was recorded from the three river systems that were relatively undisturbed and supported potential microhabitats for otters. The relative abundance of otters in the Reserve varied between 0.3 and 0.48 individuals km -1 .4. Occurrence of otters in the region was governed by the presence of habitat features such as rocky and sandy river stretches with gentle bank-slopes, bank-side vegetation serving as escape cover, and slow water current. Relatively narrow rivers with several streams joining the main course and with a large number of fallen dead trees were favoured. 5. The reservoir was an unsuitable habitat for otters owing to its steep bank-slopes (47.38 AE 1.69 ) and deep water (6.99 m AE 30.46 m). Various forms of fishing activities, followed by livestock grazing, removal of sand and boulders from the river and removal of shoreline vegetation adversely affected the presence of otter.6. Restoration of degraded habitats to meet the requirements of otters is the only option for their long-term conservation. Existing critical otter habitats should be identified and brought into the protected area network, and the wetlands and river basins forming otter habitat managed at a landscape level.

Space use by giant otter groups in the Brazilian Pantanal

“…During the wet season, groups continued to use the highest forested banks available in their territories to build dens and campsites, and some groups used emerged shrubs to build temporary platforms in marginal flooded areas and swamps. The importance of vegetation cover has been noted for other otter species (Lutrogale perspicillata- Anoop and Hussain 2004;Nawab and Hussain 2012;Lutra lutra-Macdonald and Mason 1983;Lontra provocax-Medina-Vogel et al 2003; Hydrictis maculicollis, Aonyx capensis- Perrin and Carugati 2000). The removal of riparian vegetation by canalization of rivers and streams has affected the habitat and prey of L. provocax in Chile and led to declines in density (Medina-Vogel et al 2003).…”

“…The removal of riparian vegetation by canalization of rivers and streams has affected the habitat and prey of L. provocax in Chile and led to declines in density (Medina-Vogel et al 2003). Vegetation cover on the bank seems to be important for all otter species (Anoop and Hussain 2004;Nawab and Hussain 2012) and should be considered as a key factor for the maintenance of giant otter groups.…”

The response of otters to environmental changes imposed by the construction of large dams

“…The results also illustrated a change in the availability of otter requirements over time, consistently correlated with otter marking behaviour. Otters usually forage in shallow waters (Kruuk, ; Nawab and Hussain, ), and in the Alqueva Reservoir prey capture efficiency can be expected to decrease. Although in some cases the flooding of natural deep valleys may increase the amount of shallow foraging areas, this is not the case in the Alqueva Reservoir.…”

Assessing the distribution pattern of otters in four rivers of the Indian Himalayan biodiversity hotspot

“…The locations of tracks, spraints, and other indirect and direct signs were recorded using a global positioning system. Surveying indirect signs of otters was very important, as these species are elusive and either nocturnal or crepuscular (Hussain, ; Hussain et al, ; Khan et al, ; Nawab & Hussain, ).…”