Individual differences in spatial utilization of a river-system by otters Lutra lutra

Abstract

L. S. 1996. Individual differences in spatial utilization of a river-system by otters Lutra lutra. Acta Theriologica 41: 137-147.One female and 2 male otters Lutra lutra (Linnaeus, 1758) were radio-tracked in the River Don catchment, Aberdeenshire, Scotland, between April 1988 and June 1990, and their range use patterns were compared. The males had longer total ranges than the female. The range of the larger male almost completely overlapped with that of the female, but the range of the smaller male was mainly separate from that of the female. The ranges of the 2 males only partially overlapped, with the larger male having the greatest total range, nightly range and rate of travel, and the lowest tendency to revisit areas during the night. The smaller male was relatively sedentary, using two separate core areas, whereas the other 2 otters had single core areas and frequently patrolled their total ranges. As the larger male was sexually active, but the smaller one did not appear to be, it was argued that the need to search for mates could explain some of these differences in spatial patterns. All 3 otters used tributaries more than expected based on the areas within their total ranges. This may be because riparian margins were used in greater proportion than central areas of the channel width.

Movement patterns and home range of Cape clawless otters (Aonyx capensis), affected by high food density patches

“…Similarly to L. lutra in Scotland (Kruuk, 1995;Durbin, 1996), males of A. capensis had longer ranges than females. Kruuk (1995) stated that as male L. lutra are 50% heavier than females, this alone (i.e.…”

“…Following Durbin (1996), for each tracking session the rate of range use = L/T, and revisit index = D/L were measured. D is the total distance travelled by the otter during the session (including revisited areas), T is the time it spent active during the session and L is the length of range that it used.…”

Genetic diversity and landscape genetic structure of otter (Lutra lutra) populations in Europe

“…This findings mean that local populations mate randomly and are connected by gene flow at distances not wider than a few hundred km, in agreement with results of Dallas et al (2002). Despite the potential for high dispersal (Durbin 1996), intrinsic factors, such as natal philopatry and polygyny, or extrinsic habitat barriers (e.g. topography and watershed structure, regions of unsuitable habitats) can hamper gene flow and dispersal.…”

Ranging behaviour and socio-biology of Eurasian otters (Lutra lutra) on lowland mesotrophic river systems

“…The low resources in the riverine part of the oligotrophic habitat were highlighted in one study by frequent crossings of watersheds, the maintenance of exclusive cores of non-riverine habitat, and just 14-29% of home-range area consisting of riverine habitat . Interestingly, the values for the Scottish female home-ranges were unrelated to river width Kruuk et al 1993;Durbin 1996b) and appeared to arise from otters selecting a length of terrestrial-riverine interface (Durbin 1996b). We feel that the lack of relationship with river width in the Scottish data reflects the origin of the river's productivity.…”

“…Studies that calculated home-ranges from continuous tracking data and hence included the full extent of excursive movements may give rise to more precise home-range estimates than ours (e.g. Green et al 1984;Kruuk et al 1993;Durbin 1996b).…”