Food Shortage Disrupts Social Organization: The Case of Red Squirrels in Conifer Forests

摘要: A recent conceptual model of spatial organization in vertebrates, based upon changes home range overlap with habitat quality, ‘the space-use model’, predicts large and strongly overlapping ranges absence territorial behaviour habitats poor food availability. We investigated whether the can be extended to predict intra-population variation a strong temporal resource abundance. studied space use Eurasian red squirrels (Sciurus vulgaris) subalpine conifer forests over 4 years fluctuations seed production. Norway spruce dominated are limited for squirrels, tree availability is gradually depleted year following seed-crop. Male female responded seed-crop failure 2000 by increasing their core-areas (mean MCP ± SE summer autumn, respectively: 2001, 122.9±14.1 ha 84.3±9.4 ha, against 43.0±6.4 ha 20.8±3.8 ha 2002, 22.7±1.5 ha 21.4±2.0 ha 2003). In half animals, those poorest quality pre-dispersal ranges, emigrated areas more larch. Residents had multi-nuclear core-areas. Also, intra-sexual core-area (males males, females females) was higher 2001 than autumn 2002 2003 (means males 52±8 44±7%, 80±30 15±11%, 2003, 37±19 26±14%; 52±10 112±32%, 55±27 0±0%, 12±8 0.1±0%). Red shortage moving patches other resources abandoned spacing pattern reduced among nearly exclusive females, found less variable habitats. After richer seed-crops it took about reduce size return stable territoriality adult females. These results consistent show that plastic, conditional strategy individuals adapting and/or location relation local distribution abundance resources.