Stage-specific habitat use of the Mountain Plover in Colorado

Habitat structure, food availability, and predation risk have spatiotemporal variation on the landscape that creates tradeoffs between risk and rewards for animals as they use habitat. These tradeoffs are associated with survival consequences and can vary by life or breeding stage, but stage-specific shifts in these relationships are often not considered in studies of habitat use and survival. We investigated habitat use for nests and broods in the Mountain plover as an exemplar of a ground-nesting species with precocial, mobile young to explore site- and breeding stage-specific responses to vegetation structure, food availability, and predation risk. We located and monitored nests and broods at two study sites in Colorado occupied by geographically separated breeding populations of plovers. We quantified the three covariate categories across standardized site-wide grids in 2021 and 2022. We employed a resource selection analysis to evaluate 10 a priori working hypotheses for how environmental covariates may influence the habitat used by plovers for nesting and brood-rearing. Model comparison results suggest that habitat use relative to availability is best explained by a quadratic relationship with vegetation structure dependent on breeding stage and site but not influenced by food availability or predation risk. Specifically, probability of use for nest sites was highest in areas with shorter vegetation, consistent with previous research, while probability of use for broods was lowest in areas with moderate groundcover height and bare ground coverage and highest at the extremes. These results emphasize the importance of investigating stage-specific habitat use for species with precocial young.