Washington State Snowy Plover Population Monitoring, Research, and Management: 2015 Nesting Season Research Progress Report

During the 2015 western snowy plover (Charadrius nivosus nivosus) nesting season, we monitored breeding phenology, nest success, fledging success and number of nesting adult snowy plovers in Washington. Field monitoring and research was conducted by Cyndie Sundstrom, William Ritchie, Katelyn Raby, Larissa Ritzman, with assistance from Warren Michaelis and Anthony Novack. Management activities included restricting human access to nesting sites, predator management, and restoring nesting habitat. A summary of some of our 2015 activities and results:

Breeding Phenology 

• Clutches were initiated between 7 March and 30 June (Figure 2). However, very early nests could have gone undetected because intensive surveys did not start until early April.
• The first chick known to have fledged, fledged around 30 May and the last chick known to fledge, fledged around 26 August.
• Both clutch initiation and fledging dates were unusually early this year.

Breeding Range 

• We conducted 22 surveys at 10 sites between 18 May and 7 July 2015 to either assess site occupancy status or to count the number of adults.
• Snowy plovers were only found nesting on Leadbetter Point, Midway Beach, and Graveyard Spit
• Plovers were detected on the sandy islands of Willapa Bay but we found no evidence of local breeding.

Number of Breeding Adults 

• The mean 2015 Washington breeding adult population was 77 (Range: 65-98). All of the breeding adults observed were found on Leadbetter Point, Midway Beach, and Graveyard Spit.
• From 2006-2009 the Washington snowy plover population declined annually and precipitously. From 2009-2012, the adult breeding population was fairly stable, around 31-36 birds. Since 2013, it appears that the population is now growing.

Nest success 

• Sixty nests were discovered and monitored at Midway Beach/Graveyard Spit and Leadbetter Point. Based on chicks observed on the beach, we know there were at least 16 additional nests that we did not locate.
• The percent of nests that survived from egg laying through hatching during the 2015 nesting season was approximately 70% (apparent nesting success). However, when accounting for exposure, nest success was 41% (Mayfield Method). Wire cages were not placed around nests to exclude predators (exclosures) in 2014 or 2015. This is an extremely high nest success rate for unexclosed nests and is likely attributable to USDA Wildlife Service's ongoing predator management on Leadbetter Point and the initiation of predator management at Midway Beach.
• For the third consecutive year, nest predation was not the primary source of nest failure. Corvids were the only confirmed nest predators and were identified based on tracks left at the nest. This season, human caused nest failure and nest abandonment were the primary causes of nest failure.

Fledging Success 

• The average number of young fledged per adult male on the three Washington nesting sites was 1.74 (possible range = 1.24-2.2). Population viability analyses indicate that, on average, at least one young must fledge per adult male to have a stable population (Nur et al. 1999). This fledging rate is the highest that we have ever observed and may again be attributed to predator management.

Management Actions 

• Restrictions: Fireworks were prohibited on beaches where State Parks and U.S. Fish and Wildlife Service (USFWS) are the upland land owners.
• Nest exclosures: No nests were exclosed in 2015.
• Signing: In an effort to protect nests, approximately 8.0 miles of beach at Leadbetter Point and approximately 1.3 miles of beach at Midway Beach were signed to restrict human access on the dry portions of the beach. Access restrictions on private land only occurred when permitted by the land owner. New signs were purchased and now all signs have a similar appearance and message regardless of land ownership.
• Clam tides: Washington Department of Fish and Wildlife and US Fish and Wildlife coordinated law enforcement activities especially during clam tides. A federal fish and wildlife officer helped keep people out of closure areas at Leadbetter Point during clam harvest openings. Portable toilets were again placed on the beach at Leadbetter to minimize intrusions into the closed nesting habitat.
• Nest Predation: Predator management was conducted by wildlife specialists with USDA APHIS Wildlife Services on both Leadbetter Point and Midway/Grayland Beach in 2015. Management consisted of dispersing or targeted lethal removal of known nest predators (corvids) in or adjacent to the plover nesting areas. Early results suggest that this activity was successful in increasing nest hatching rates and fledging rates.
• Restoration: The Willapa NWR habitat restoration area (HRA) at Leadbetter Point now totals more than 400 acres and the restoration area on Washington State Parks land at Leadbetter Point was expanded to 15 acres. These areas have been mostly cleared of non-native beachgrass using mechanical and chemical methods.