Abstract

Snowy plovers (Charadrius nivosus) are small, ground-nesting shorebirds that are a species of conservation concern throughout North America. Despite increased efforts to understand factors contributing to the decline of snowy plover, little is known about habitat selection and breeding ecology of snowy plover for the large population found in the Great Basin. We tested hypotheses concerning the occupancy and nesting success of snowy plover. First, we identified factors influencing snowy plover nest survival at Great Salt Lake, Utah. We hypothesized that snowy plover would demonstrate differences in nest survival rates across years due to differences in habitat characteristics, predator abundance, human influence, resource availability, and fluctuating water levels. We conducted nest surveys at five sites along the Great Salt Lake to locate new nests or monitor known nests until nest fate was determined. We found 608 nests between 2003, 2005-2010, and 2012. The most common cause of nest failure was predation, followed by weather, abandonment, and trampling. Nest survival estimates ranged from 4.6 -- 46.4% with considerable yearly variation. There was no correlation between researcher activity (visits to nests and trapping of adults) and nest survival. Nests in close proximity to roads had lower survival than nests far from roads. Nests located on barren mudflats also had lower survival than nests in vegetated areas or near debris. We found that nests had a higher probability of survival as they increased in incubation stage. Because nesting areas around the Great Salt Lake host some of the largest concentrations of breeding snowy plover in North America, we suggest that managers consider measures to maintain suitable nesting habitat for snowy plover. Second, we determined factors affecting snowy plover occupancy and detection probabilities in western Utah between 2011 and 2012. We hypothesized that snowy plover would be associated with spring water flows and sparsely vegetated salt flats. We made repeated visits to randomly selected survey plots recording the number of snowy plover adults and habitat characteristics within each plot. We modeled the relationship between snowy plover detection probability and habitat and environmental characteristics. The detection probability was 77% (95% CI = 64 -- 86%) and did not vary by year. There was a positive relationship between ambient temperature and detection probability. Next, we modeled the relationship between snowy plover occupancy and individual habitat characteristics including distance to water, distance to roads, land cover types, and vegetative characteristics. Snowy plover occupancy did not vary by year and was estimated at 12% (95% CI = 7 -- 21%). Occupancy was best predicted by close proximity to water, playa land cover, and minimal shrub cover. We used habitat characteristics that best predicted snowy plover occupancy to generate a predictive habitat model that can help prioritize future snowy plover surveys and guide conservation efforts.

Degree

College and Department

Life Sciences; Plant and Wildlife Sciences

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