Spacing out at Mono Lake: Breeding Success, Nest Density, and Predation in the Snowy Plover

Snowy Plovers (Charadrius alexandrinus) nesting on the exposed lake bed surrounding Mono Lake, California lose up to 40% of their clutches. Most are destroyed by predators, predominantly California Gulls (Larus californicus). In 1978 Snowy Plover reproduction was estimated at 0.49-0.70 fledged young per female. Population stability was estimated to require 0.80 fledged young per female. A series of experiments with artificial clutches placed at different densities in the nesting area demonstrates that the predators can have an effect on the plovers' nesting success that is dependent upon their nest density. The maintenance of low nesting density is an important antipredator adaptation. We consider predation on clutches and broods to be the major limiting factor on the Snowy Plover population at Mono Lake.