Decomposing an elevational gradient in predation by insectivorous birds

Insectivorous birds have ecologically important effects on prey abundance, behavior, and evolution, and through top-down control birds indirectly reduce herbivory and promote plant growth. While several studies sought to characterize biogeographic patterns in top-down control by birds, variation in bird predation along elevational gradients is not well characterized both in terms of its commonness and the mechanisms underlying such variation. Here we characterized variation in bird predation along a 700m montane elevation gradient using artificial clay caterpillars, assessing the roles of variation in aridity, other elevational effects not associated with aridity (e.g., most notably growing season length) and bird abundance and diversity. Multivariate models revealed attack rates increasing with aridity (when controlling for the effects of elevation) and elevation (when controlling for aridity). Because aridity declines with elevation, elevational patterns were not detectable in a univa..., Clay caterpillars were placed on aspen trees at 10 sites within a valley, at 5 valleys along an elevational gradient in the Rocky Mountains. Attack rates by birds were recorded from the clay caterpillars on either 3 or 4 seperate dates per site. Data of attack are reported as a proportion of the 20 caterpillars at 1 site on 1 date that were attacked (76 total). We reported aridity as a PCA of temperature and precipiation. We reported the bird community using eBird checklists from the same region as the valleys, and extracted this following \"Best practices for Using eBird data\". , R Studio, # Decomposing an elevational gradient in predation by insectivorous birds

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Clay caterpillars were placed on aspen trees at 10 sites within a valley, at 5 valleys along an elevational gradient in the Rocky Mountains. Attack rates by birds were recorded from the clay caterpillars on either 3 or 4 separate dates per site. Data of attack are reported as a proportion of the 20 caterpillars at 1 site on 1 date that were attacked (76 total). We reported aridity as a PCA of temperature and precipitation.

We reported the bird community using eBird checklists from the same region as the valleys, and extracted this following \"Best practices for Using eBird data\". Data on the climate and on the bird community were sourced from public databases (PRISM and eBird respectively). The published code provides the parameters to which we extracted this data from these public sources, and also provides code for how these data were wrangled and thus used.

## Description of the data and file structure

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