Washington State Snowy Plover Population Monitoring, Research, and Management: 2023 Nesting Season Research Progress Report

During the 2023 western snowy plover (Charadrius nivosus nivosus) nesting season, we counted the number of adult snowy plovers at potential nesting sites in Washington and monitored breeding phenology, nest success, and fledging success at Empire Spit (previously part of Graveyard Spit). Work was conducted by Washington Department of Fish and Wildlife, US Fish and Wildlife Service, and Shoalwater Bay Indian Tribe. Management activities included restricting human access to nesting sites and restoring nesting habitat.

Thirty breeding surveys at eleven sites were conducted between 22 May and 03 July 2023 to assess site occupancy status or to count the total number of adults detected. The mean 2023 Washington breeding adult population was 63 (range: 54-68). Breeding adults were observed at Copalis Spit, Conner Creek, Midway Beach, Empire Spit, North Willapa Bay Islands, and Leadbetter Point.

A total of 49 snowy plover nests were observed on Washington beaches at Copalis Spit, Conner Creek, Midway, Empire Spit, North Willapa Bay Islands, and Leadbetter Point. Only Empire Spit was monitored closely enough to estimate nest and fledging success. Thirty-five nests were detected and monitored at Empire Spit. Eighteen (51%) of the 35 nests hatched. Predation was the primary cause of nest failures, with nine lost to raven predation, three to unknown corvids, and two to coyote predation. The average number of young fledged per adult male was 2.46 (range: 1.45-4.00). Even the low estimate (1.45) indicates a growing population at Empire Spit. While this is the first time since 2018 that we have an estimate for fledging success, it is likely not representative of the overall fledging success for all Washington sites, as Empire Spit has historically had higher nesting and fledging success compared to Washington’s other primary nesting sites.