The Pacific coastal population of the Western Snowy Plover (Charadrius alexandrinus nivosus) is listed as Threatened under the Endangered Species Act, and is listed as Endangered by Washington State. The current Pacific coast breeding population extends from Midway Beach, Washington, to Bahia Magdalena, Baja California, Mexico. The Snowy Plover winters mainly in coastal areas from southern Washington to Central America. This coastal population nests primarily above the high tide line on a variety of beach and dune types including coastal beaches, sand spits, dune-backed beaches, sparsely-vegetated dunes, beaches at creek and river mouths, and bluff-backed beaches (U.S. Fish and Wildlife Service 2007). It also nests on sandy river bars, salt pans at lagoons and estuaries, salt pond levees, dry salt ponds, and on dredge spoils (U.S. Fish and Wildlife Service 2007). In winter, Snowy Plovers are found on many of the beaches used for nesting as well as on beaches where they do not nest (U.S. Fish and Wildlife Service 2007).
According to the U.S. Fish and Wildlife Service (2007), "Habitat degradation caused by human disturbance, urban development, introduced beachgrass (Ammophila spp.), and expanding predator populations have resulted in a decline in active nesting areas and in the size of the breeding and wintering populations". In Washington, predators eating plover eggs, weather, shoreline modification, dune stabilization, and recreational activities have been attributed to reduced nest success and have been cited as the causes of local population declines (Washington Department of Fish and Wildlife 1995).
Historically, five areas supported nesting plovers in Washington (Washington Department of Fish and Wildlife 1995). Today, snowy plovers can only be found nesting on three nesting sites.
Both the federal and state recovery plans require monitoring of breeding adults and monitoring of fledging success to assess progress toward recovery goals. Monitoring is also necessary to evaluate the impact of conservation actions on plover populations such as the use of wire nest exclosures to exclude potential predators and the effectiveness of habitat restoration efforts. WDFW research is focused on addressing these research needs.
This work is funded by U.S. Fish and Wildlife Service and WDFW.
- The percent of nests that survived from egg laying through hatching during the 2013 nesting season was approximately 50% (includes exclosed and non-exclosed nests) which is extremely unusual. The nest success at Leadbetter Point (the site with the lowest nest success in past years) was extraordinarily high, with 79% nest success. This was the first year that predator management was implemented in Washington and it was only implemented at Leadbetter Point.
- For the first time, nest predation was not the primary source of nest failure. Common ravens were the only identified nest predator and were identified based on tracks left at the nest. However, in several cases we could not identify the nest predator.
- Adult population counts were declining precipitously through 2012 but with a higher average count in 2013, the decline is no longer significant at the p = 0.05 level, but is still significant at the p = 0.10 level (See graph).
- The average number of young fledged per adult male on the three nesting sites in Washington was 1.04 (range = 0.92-1.18). Population viability analyses indicate that, on average, at least one young must fledge per adult male to have a stable population.