T = 15.87° Queen Charlotte Islands land birds
(Simberloff and Martin 1991)

Fig. 7. The hotter matrices of non-insularized species. Because of their inherent mobility, migratory birds will generally exhibit much warmer matrix temperatures than well-insularized species which were part of the ancestral biota. The nested patterns for the birds of the Queen Charlotte Islands are clearly not due to the biogeographic extinction event of the archipelago. Rather, their nestedness undoubtedly reflects the underlying nested structure of suitable habitat. In addition to the intrinsically elevated matrix temperature of the Queen Charlotte birds (see text), six species further exhibit idiosyncratic temperatures near or greater than system temperature. They are (left to right): chestnut-backed chickadee, Parus rufescens, song sparrow, Melospiza melodia, orange-crowned warbler, Vermivora celata, bald eagle, Haliaeetus leucocephalis, rufous hummingbird, Selasphorus rufus, and the fox sparrow, Passereillia iliaca. Competitive exclusion has been proposed as the mechanism promoting the idiosyncratic distributions of the generalist species (Simberloff and Martin 1991), forcing the generalists to appear principally on the smaller islands. However, competitive exclusion is not likely to be an adequate explanation for the idiosyncratic distributions of the bald eagle or the rufous hummingbird.