The Distribution and Reproductive Success of the Western Snowy Plover along the Oregon Coast - 2011

Abstract

From 6 April – 19 September 2011 we monitored the distribution, abundance and productivity of the federally Threatened Western Snowy Plover (Charadrius nivosus nivosus) along the Oregon coast. From north to south, we surveyed and monitored plover activity at Sutton Beach, Siltcoos River estuary, the Dunes Overlook, North Tahkenitch Creek, Tenmile Creek, Coos Bay North Spit, Bandon Beach, New River, and Floras Lake. Our objectives for the Oregon coastal population in 2011 were to: 1) estimate the size of the adult Snowy Plover population, 2) locate plover nests, 3) continue use of mini-exclosures (MEs) to protect nests from predators when and where needed, 4) determine nest success, 5) determine fledging success, 6) monitor brood movements, 7) collect general observational data about predators, and 8) evaluate the effectiveness of predator management. We observed an estimated 247-253 adult Snowy Plovers; a minimum of 214 individuals were known to have nested. The adult plover population was the highest estimate recorded since monitoring began in 1990. We monitored 289 nests in 2011, the highest number of nests since monitoring began in 1990. Overall apparent nest success was 50%. Exclosed nests (n = 48) had a 71% apparent nest success rate, and unexclosed nests (n = 241) had a 48% apparent nest success rate. Nest failures were attributed to unknown depredation (22%), corvid depredation (20%), unknown cause (18%), one-egg nests (16%), abandonment (15%), wind/weather (3%), mammalian depredation (2%), adult plover depredation (2%), infertility (1%), and rodent depredation (1%). We monitored 148 broods, including four from unknown nests, and documented a minimum of 168 fledglings. Overall brood success was 71%, fledging success was 46%, and 1.57 fledglings per male were produced. Continued predator management, habitat improvement and maintenance, and management of recreational activities at all sites are recommended to achieve recovery goals.