Data from: Biotic interactions help explain variation in elevational range limits of birds among Bornean mountains
Cite this dataset
Burner, Ryan C. et al. (2023). Data from: Biotic interactions help explain variation in elevational range limits of birds among Bornean mountains [Dataset]. Dryad. https://doi.org/10.5061/dryad.bg79cnp74
Abstract
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 birds on four mountains in Borneo to test which environmental variables—habitat zone compression or presence of likely competitors—best predicted differences in elevational ranges of species among mountains. For this purpose, we used two complementary tests: a comparison of elevational range limits between pairs of mountains, and linear mixed models with naïve occupancy as the response variable.
Results
We found that lowland species occur higher in elevation on two small mountains compared to Mt. Mulu. This result is inconsistent with the expectation that distributions of habitats are elevationally compressed on small mountains, but is consistent with the hypothesis that a reduction in competition (likely diffuse) on short mountains, which largely lack montane specialist species, allows lowland species to occur higher in elevation. The relative influence of competition changes with elevation, and the correlation between lower range limits of montane species and the distribution of their competitors was weaker than in lowland species.
Main conclusions
These findings provide support for the importance of biotic interactions in setting elevational range limits of tropical bird species, although abiotic gradients explain the majority of distribution patterns. Thus, models predicting range shifts under climate change scenarios must include not only climatic variables, as is currently most common, but also information on potentially resulting changes in species interactions, especially for lowland species.
Methods
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).
Usage notes
README file included in the Excel file.
Funding
National Science Foundation, Award: DEB-1241059
National Science Foundation, Award: DEB-1241041
National Science Foundation, Award: DEB-1651283
National Science Foundation, Award: IOS-1656120
National Geographic Society, Award: 8753-10
American Indonesian Exchange Foundation, Award: Fulbright Fellowship to RCB
Louisiana Board of Regents, Award: Graduate fellowship to RCB
Wesley M. Dixon Memorial Fellowship, Award: Fellowship to AJB
American Ornithological Society, Award: AOU Graduate Student Research Grant to AJB