Mountain Plover habitat selection and nest survival in relation to weather variability and spatial attributes of black-tailed prairie dog disturbance

Authors: DUCHARDT, COURTNEY - University Of Wyoming; BECK, JEFF - University Of Wyoming; Augustine, David

Submitted to: The Condor: Ornithological Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2019
Publication Date: 2/3/2020
Citation: Duchardt, C., Beck, J., Augustine, D.J. 2020. Mountain Plover habitat selection and nest survival in relation to weather variability and spatial attributes of black-tailed prairie dog disturbance. The Condor: Ornithological Applications. 122(1):1-15. https://doi.org/10.1093/condor/duz059.
DOI: https://doi.org/10.1093/condor/duz059

Interpretive Summary: Birds that breed in grasslands of the Great Plains are one of the most rapidly declining groups of birds in North America. In the western Great Plains, some bird species, such as the Mountain Plover, use black-tailed prairie dog colonies as breeding habitat. Prairie dogs have declined across much of their range, which may have implications for Mountain Plover populations. Little is known about how Mountain Plovers use very large (e.g. > 1,000 acre) prairie dog colonies because such large colonies are currently rare. We studied Mountain Plover habitat utilization, nest-site selection, and nest success in one of the large prairie dog colony complexes remaining in the Great Plains in the 21st century. Plover abundance was highest on older, “medium”-sized (250–1,250 acre) colonies with high cover of annual forbs and bare ground (2.2 birds/mi2), but lower on extremely large (>5,000 acre) colonies (0.8 birds/mi2). Plovers were most abundant in areas with high exposure of bare ground, and low cactus cover. Nest survival rates were greater for older nests, nests with low cactus cover, and time periods with lower daily temperatures. Also, we found that nests failed for two different reasons: nest predation versus nest abandonment/egg inviability. Harsh weather (e.g. thunderstorms) and higher temperatures were associated with nest abandonment or egg inviability. Our work shows that the value of prairie dog colonies varies across the landscape, and is optimized in moderatly sized colonies.

Technical Abstract: Habitat loss and altered disturbance regimes have led to declines in many species of aridland birds, including the imperiled Mountain Plover (Charadrius montanus). In certain parts of their range Mountain Plovers rely almost exclusively on Black-Tailed Prairie Dog (Cynomys ludovicianus) colonies as nesting habitat. Previous studies have examined Mountain Plover nest and brood survival on prairie dog colonies in portions of their range, but little is known about how colony size and shape influence these vital rates or patterns of habitat selection. We examined how 1) adult habitat utilization, 2) nest-site selection, and 3) nest success responded to a suite of local- and site-level variables on large prairie dog colony complexes in northeastern Wyoming. Adult abundance was highest on older, “medium”-sized (100–500 ha) colonies with high cover of annual forbs and bare ground (5.8 birds/km2), but lower on extremely large (>2000 ha) colonies (2.1 birds/km2). Variability in the amount of bare ground within colonies was a significant predictor of adult distribution and nest placement, while birds avoided areas of high cactus cover at the nest-site scale. Nest survival was higher for older nests, and nests with lower cactus cover, and decreased with increasing temperatures. Uncertainty was high for models of daily nest survival, potentially because of two competing sources of nest failure: nest depredation and nest abandonment or inviability of eggs. Drivers of these two sources of nest failure differed, with inclement weather and higher temperatures associated with nest abandonment or egg inviability. We highlight how different habitat features influence bird abundance and nest distribution at different temporal and spatial scales, and that ecosystem engineering by Black-Tailed Prairie Dogs may vary widely across the landscape. Furthermore, our work reveals how partitioning the causes of nest failure during nest survival analyses enhances understanding of survival rate covariates, especially for species that experience harsh and unpredictable weather conditions.