Globally, relationships between avian richness and elevation in mountain ecosystems typically reflect one of four well-documented patterns, but the mechanisms responsible for these patterns are poorly understood. We investigated which pattern best described bird species richness in peatlands of the Upper Bow Basin of the Canadian Rocky Mountains (1300 to 2000 m a.s.l.) and used a model competition framework to investigate possible mechanisms. Avian richness displayed a plateauing (cubic) relationship in response to increasing elevation (AICc weight = 0.48). Log richness was significantly positively related to log peatland area (R² = 0.42, p = 0.001); however, once we accounted for the richness-area relationship (area was not related to elevation (R² = 0.13, p = 0.083)), the richness-elevation relationship was best described by a negative linear model rather than a cubic model (AICc weight = 0.69, R² = 0.39). Consequently, we reject the neutral model of the mid-domain effect and conclude that peatland area and one or more environmental filters are simultaneously driving relationships between avian richness and elevation in Rocky Mountain peatlands. Multi-causality likely explains why researchers in different geographies observe inconsistent patterns between richness and elevation: drivers and interactions among drivers may vary spatially. Importantly, Natural Subregion was a stronger predictor of avian species richness than elevation per se (AICc weight = 0.96), suggesting that the responsible environmental filter(s) is relatively homogenous within ecological land classes (e.g., primary productivity) rather than directly variable with elevation (e.g., temperature). The results also lend insight into priorities for future research on richness-elevation patterns in mountain birds.

Data was collected from 24 peatlands situated in the Upper Bow River Basin on the eastern slopes of the Rocky Mountains across a range of elevation. Avian diversity was determined from transcriptions of recordings made with SM4 Automated Recording Units deployed in May 2019 and collected in June 2019. Details are published in the associated manuscript published in the article "Habitat area and environmental filters determine avian richness along an elevation gradient in mountain peatlands" published in the Journal of Avian Biology and in the 2020 MSc. thesis by Jordan Reynolds from the University of Waterloo, titled "Avian species richness elevational patterns in mountain peatlands." This thesis can be accessed for free online at https://uwspace.uwaterloo.ca/handle/10012/16127. The attached files have a tab of data and a second tab describing the column headings, which provide descriptions of how data were treated.

There are no readme files. There are no missing data. There are three excel files with two worksheets in each. the first gives the data and the second provides a description of the data or definition of the column headings in the first worksheet. One worksheet gives the avian richness, size, elevation, and site ID for each peatland. The second gives the presence-absence data for all detected bird species at each peatland. The third characterizes the species accumulation curve for each peatland to contextualize the sufficiency of our sampling effort.