Biotic interactions help explain variation in elevational range limits of birds among Bornean mountains

Aim Physiological tolerances and biotic interactions along habitat gradients are thought to influence species occurrence. Distributional differences caused by such forces are particularly noticeable on tropical mountains, where high species turnover along elevational gradients occurs over relatively short distances and elevational distributions of particular species can shift among mountains. Such shifts are interpreted as evidence of the importance of spatial variation in interspecific competition and habitat or climatic gradients. To assess the relative importance of competition and compression of habitat and climatic zones in setting range limits, we examined differences in elevational ranges of forest bird species among four Bornean mountains with distinct features. Location Bornean mountains Kinabalu, Mulu, Pueh and Topap Oso. Taxon Rain forest bird communities along elevational gradients. Methods We surveyed the elevational ranges of rain forest ..., These data estimate the occupancy of each bird species at each elevation on each of four mountains in Borneo. Species detected fewer than 10 times on a given mountain are excluded. This 'naive occupancy' value was estimated by dividing the number of points where the species was detected on a given mountain at a given elevation by the total number of points at that elevation. Points were lumped into elevational bins; see manuscript. Also includes estimates of the summed occupancy of potential competitors of the same genus and of the same foraging guild (these estimates are obtained as above). , README file included in the Excel file.