Washington State Snowy Plover Population Monitoring, Research, and Management: 2016 Nesting Season Research Progress Report

During the 2016 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 2016 activities and results:

Breeding Phenology

• Clutches were initiated between 2 April and 11 July (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 5 June and the last chick known to fledge, fledged around 11 Sept.
• There was an early and a mid-season peak in both clutch initiation and fledging.

Breeding Range

• We conducted 17 surveys at 12 sites between 16 May and 13 July 2016 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 and nesting was confirmed on one island in Willapa Bay and a lone banded female was detected at Copalis Spit who returned to Graveyard Spit to nest.

Number of Breeding Adults

• The mean 2016 Washington breeding adult population was 93 (Range: 85-100). Breeding adults were observed on Leadbetter Point, Midway Beach, Graveyard Spit, Copalis Spit and on an island in Willapa Bay off Leadbetter Point.
• 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, the population has been growing at a high rate.

Nest success

• One hundred and fourteen nests were discovered and monitored at Midway Beach/Graveyard Spit, Leadbetter Point, and an island off the tip of Leadbetter Point. Based on chicks observed on the beach, we know there were at least 5 additional nests that we did not locate. Not all nests were observed regularly and are therefore not included in the numbers below when assessing outcome.
• The percent of nests that survived from egg laying through hatching during the 2016 nesting season was approximately 66% (apparent nesting success). When accounting for exposure, nest success was almost identical = 67% (Mayfield Method). Wire cages were not placed around nests to exclude predators (exclosures) in 2014-2016. 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 Midway Beach.
• For the fourth consecutive year, nest predation was not the primary source of nest failure. Corvids and a coyote were the only confirmed nest predators identified from tracks left at the nest. This season, wind-blown sand and human activities were the primary non-predator sources of nest failure.

Fledging Success

• The average number of young fledged per adult male on the three Washington nesting sites was 0.96 (0.74-1.21). 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). The fledging rate for the past four years has been approximately 1.0 or greater which suggests a stable to growing population.

Management Actions

• Nest exclosures: No nests were exclosed in 2016.
• Signing: In an effort to protect nests from human activities, 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 where 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 coordinated law enforcement activities especially during clam tides. All claming was prohibited at Miday due to high levels of the toxin domoic acid. A total of 94 days were open to recreational razor clamming at Long Beach in 2016 (7 January – 8 May). Thirty-nine of those days were during the plover breeding season (an increase of 62% over 2015). 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 2016. Management consisted of dispersing or targeted lethal removal of known nest predators (corvids) in or adjacent to the plover nesting areas. Results suggest that this activity is 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.