Western Snowy Plover Breeding Dispersal in Response To Nest Failure in Monterey Bay, California, USA
Abstract
We examined short-distance breeding dispersal between nesting attempts of the serially polygamous western snowy plover Anarhynchus nivosus nivosus, a federally threatened species in Monterey Bay, California, USA, during 2013–2020. We compared distances dispersed by both sexes and after various nesting outcomes. Dispersal distances within-season were generally shorter for males than females, but similar between seasons depending on nest success. We compared dispersal distances for different causes of nest failure (human disturbance, predation, environment, abandonment, and unidentified) and different predator types. Plovers with nests that failed due to human activities dispersed an average distance of 1872 m, while those with depredated nests dispersed an average of 1161 m; 58 and 31% farther, respectively, than plovers with nests that failed owing to environmental causes. However, we found no difference in dispersal distance between predator types. A best subset multiple regression model was used to determine whether winter migration status, nesting success, cause of nest failure, cumulative nests, or cumulative failed nests influence plover dispersal. Nesting success was a strong predictor variable of dispersal distances for males and females, with winter migration status adding more predictive power to the model for males. Current climate change projections suggest an increased likelihood of environmental instability, which could increase the number of nest failures to environmental causes over time. Future research should further assess the vulnerability of nesting plovers to environmental factors (e.g. sea level inundation), given the minimal predictive power of dispersal for nesting success. We hope this information can assist conservation efforts with monitoring and habitat protection.
