Characterizing habitat preference of Eurasian river otter (Lutra lutra) in streams using a self-organizing map

Abstract

We studied the habitat preferences of Eurasian river otters (Lutra lutra) using the distribution patterns of the numbers of spraints and sprainting spots of otters, as well as related environmental variables (habitat zone, river management, bank type, vegetation coverage, width, depth, etc.) in two streams. The numbers of otter spraints and sprainting spots were sampled monthly in two streams on Geoje Island, Republic of Korea, from January to December 2004. Additional environmental variables were measured at the sampling sites. A self-organizing map (SOM), which is an unsupervised artificial neural network, was used to characterize the habitat preferences of otters. In our results, the SOM classified three different groups of study sites based on their habitat conditions, and the habitat differences were effectively visualized on the trained SOM map. Otters showed spatial and temporal dynamics in the numbers of spraints and sprainting spots, and revealed habitat preferences for shallow, narrow areas of streams and edges of water that were not far from reservoirs but covered with trees and shrubs. Additionally, otters preferred an environment in which weirs reduced the drift of water and gathered fishes and had a natural type of stream bank; these findings are relevant for river management. Otters adapted to places close to roads, residential areas, and agricultural areas with some tolerance of human interference.

Conservation of the Asian Small-Clawed Otter (Aonyx Cinereus) in Human-Modified Landscapes, Western Ghats, India

“…While the small-clawed otter has been shown to have a high occupancy in streams in protected areas [29], the present study demonstrates a similarly high occupancy in human-modified landscape adjoining protected areas. This is consistent with reports for other species of otters whose occupancy seems to be fairly insensitive to human-modified landscapes [21,23,43–48]. A major reason for this is perhaps the linear nature of their habitats, which enables otters to travel over longer distances to meet their requirements in comparison to land mammals of similar body size.…”

Diet composition of the Eurasian otter Lutra lutra in different freshwater habitats of temperate Europe: a review and meta‐analysis

“…This indicates that in such open habitats, alternative prey is of special importance. Indeed, otters prefer habitats with riparian or lacustrine vegetation that they can use as shelter, and some research shows that otters may be threatened by clearing of stream-side vegetation (Cho et al 2009).…”

Utilização de abrigos e latrinas por Lontra longicaudis (Olfers, 1818) em um arroio costeiro na Área de Proteção Ambiental da Lagoa Verde, Rio Grande do Sul, Brasil

“…Kruuk (2006) também afirma que a disponibilidade de alimento é o principal fator ambiental regulador da ocorrência de lontras em determinado sistema. No entanto, diversos estudos baseados em distribuição dos sítios de defecação ou rádio-telemetria indicam uma maior utilização das margens providas de vegetação ripária arbustiva e/ou arbórea, como observado para Lutra lutra (Jenkins e Burrows, 1980;Macdonald e Mason, 1985;Mason e Macdonald, 1987;Durbin, 1998;Cho et al, 2009), Lontra provocax (Medina-Vogel et al, 2003;Sepúlveda et al, 2007) e L. longicaudis (Alarcon e Simões-Lopes, 2003;Carrilo-Rubio e Lafón, 2004). Estes dados, portanto, evidenciam a importância da preservação da vegetação ripária para a manutenção dos recursos espaciais utilizados por L. longicaudis e outras espécies de lontras nas margens dos sistemas fluviais.…”