Elevated temperatures drive fine-scale patterns of habitat use in a savanna bird community

Many animals use thermally buffered microhabitats, e.g. patches of shade within trees, to avoid temperature extremes. These thermal refugia' may mediate the impact of climate change on animals. Predicting how species and communities will respond to rising temperatures therefore requires an understanding of the availability of these refugia and how animals use them. We investigated patterns of tree use by birds in the southern Kalahari across different times of day and days of varying maximum air temperature. On hot' days (>35 degrees C) birds showed increased preference for trees that provided the greatest density of shade (Boscia albitrunca), and this effect was particularly pronounced at the hottest times of day. Comparisons of focal bird species with differing foraging niches revealed interspecific differences in tree use. Two arboreally foraging species showed a similar preference for B. albitrunca on both cool' and hot' days. In contrast, two ground-foraging species increased their use of B. albitrunca trees on hot days, with one species (Scaly-feathered Finch Sporopipes squamifrons) changing its behaviour from avoiding to preferring this tree. We discuss the role of B. albitrunca trees as thermal refugia and the implications of temperature-driven changes in tree use in the context of rising temperatures due to climate change.