Effect of energetic constraints on distribution and winter survival of weasel males.

摘要: 1. The absolute energy needs of small animals are generally lower than those larger animals. This should drive higher mortality animals, when the environmental conditions deteriorate. However, demonstration effect constraints on survivals proved difficult, because range body mass within species is too to produce enough variation for studying such an effect. An opportunity intraspecific study comes from weasels inhabiting Bialowieza Forest (north-eastern Poland), which characterized by a threefold in mass. 2. We assumed that summer weasel males favoured sexual selection, they more successful competing mates. then tested whether suffer winter, have difficulty finding sufficient food satisfy their and/or additional foraging time would result increased exposure predation. 3. measured daily expenditures (DEE) overwintering using doubly labelled water (DLW) technique. constructed energetic model predicting how individuals different size able balance budgets feeding large and prey while minimizing spent hunting, thereby reducing own 4. predicted our corresponded very well with distribution three habitats area. Larger were compensate requirements available smaller male weasels. effectively offset expected negative association between winter survival considerations balance. 5. Our results show affect spatial segregation at intra-specific level not only across geographical ranges, but also relatively