What preys on piping plover eggs and chicks?

摘要

Recovery of the imperiled northern Great Plains population of piping plovers (Charadrius melodus) largely depends on reducing predation on the plover's eggs and chicks, but sources of predation are poorly understood. We examined differences in the productivity of piping plovers managed by various predator exclosure options from central North Dakota to northeastern Montana during 1994-2002 (n=1,288 nest records and n=987 fledgling production records examined). Plover nest success (Mayfield estimate) increased significantly when nests were protected from mammalian predators. However, no further increase in nest success occurred when avian predators also were excluded from nests. This suggests that mammals were more important predators of piping plover eggs than were birds. The percentage of chicks lost between hatching and fledging stages when no exclosures were available to protect chicks (about 50%) was no different than the percentage lost when chicks were protected from mammals. We thus attributed nearly all predation on chicks to avian sources. We identified 5 bird and 8 mammal species or species groups as known or likely predators based on field evidence. Management to reduce local abundance of large gulls (Larus spp.) and American crows (Corvus brachyrhynchos) should be included among the tools available to sustain increased levels of plover reproductive success on prairie alkali lakes.