Poor start to snowy plover nesting season

06/13/2019

Western snowy plovers, federally threatened shorebirds that stand just six inches tall, likely struggled in the winter’s heavy storms. Biologists in the Point Reyes National Seashore are seeing fewer nests than expected on the dunes of the bird’s breeding beaches. 

As of last week, just 18 plover nests have been found in the park since breeding season began in March, two on Limantour Beach and the remaining on Great Beach between the South Beach parking lot and the Kehoe Beach trail. Last year, there were 28 nests by the start of June.  

Dave Press, the park’s ecologist, said that although storms pose challenges—considering the elevated threat of heavy wind and surf and the reduction of beach habitat—it is also possible that the Point Reyes population has reached its peak and that this is the beginning of a leveling out. 

It is too early to tell, however, since breeding lasts through September.

Most of the nests counted so far have failed, although that’s fairly typical. Only four nests are currently active; ravens, one of the birds’ most aggressive predators, have preyed on at least eight of them. As of last week, four chicks have hatched.

Plovers typically lay two to three eggs, hiding them in plain sight in shallow depressions in the sand they line with shells, sticks or other debris. The shore detritus of their nests—known as “scrapes”—together with the plovers’ white and grey-brown feathers camouflage the eggs while the parents rotate their perch during a month-long incubation. 

Female plovers can take days to pick a desirable location to nest, seeking a spot above the high-tide line but away from encroaching grasses or animals.

As soon as the chicks hatch, the female finds another free male to start a new nest, leaving the male solely responsible to raise the chicks. He usually tends to them for another month, until they fledge. 

The United States Fish and Wildlife Service listed Western snowy plovers as threatened in 1993, and the park estimates there are just 2,500 breeding birds along the Pacific Coast. Statewide, the nesting habitat for plovers was halved between 1970 and 2001. 

Per recovery recommendations from Fish and Wildlife, the seashore has a goal of hosting 64 adult breeding birds. But the park has yet to see those returns: past years included a high of 40 nesting birds in 2017; there were 39 in 2016, 29 in 2014, and just nine in 2012, a low attributed to drought.

The seashore won’t have final estimates for breeding individuals until the end of August, after numbers recorded from biologists up and down the coast have been compared. 

Some plovers migrate up or down the coast in the winter, but others stay in the seashore year-round. Mr. Press has yet to see a handful of adult birds that have nested in the seashore year after year, and he fears they didn’t make it through the winter. 

Matt Lau, an ecologist for the park who specializes in snowy plovers, wrote to the Light that research “has shown that plovers favor wide open beach habitats, and the storms this past winter have definitely narrowed sections of the beach.” 

He also said that El Nino weather patterns may affect their food availability, though that was his own conjecture. 

Based on nest counts and preliminary numbers, Mr. Lau said, “I can make an educated guess that the population [in the seashore] this year seems to have decreased.”

Since 1995, the seashore has partnered with Point Blue Conservation Science, formerly the Point Reyes Bird Observatory, and Point Reyes National Seashore Association to implement a recovery project. Efforts have included fencing and caging nesting sites, fighting European beachgrass and managing predators.

In conjunction with the recovery program, the park began restoring dunes at Abbotts Lagoon in 2001 to increase nesting habitat. Fifty acres of European beachgrass and iceplant were removed between 2001 and 2005, and beginning in 2011, the park cleared another 250 acres immediately south of Abbotts Lagoon. Current restoration efforts are moving toward North Beach. 

The park has also closed the section of Great Beach between Abbotts Lagoon and the North Beach parking lot on weekends and holidays during the summer since 2016, to protect breeding habitat from heavier foot traffic. 

Peak snowy plover breeding season coincides with peak visitation, so biologists fence off specific nesting areas along Great, Kehoe and Limantour Beaches during that time, and docents monitor the sites on weekends.  

Last week, the park newly closed a half-mile stretch of beach between the North and South Beach parking lots to pets through Sept. 30 to protect several plover nests.  

“It’s so important to respect the closures,” Mr. Press said. “The biggest concern we have is around dogs: there is no area in the park where you can have dogs off leash, but we know they are sometimes and that off-leash dogs don’t respect the fencing areas. It’s so easy for them to wander right in.”

Mr. Press added that it is important to remove food scraps from beaches, as garbage attracts predators like ravens, gulls, foxes, coyotes, skunks and raccoons. He added that his staff works with park ranchers in order to limit ravens’ access to supplemental feed and shelter—such as from the large barns—which help allow for a large population on the outer peninsula. 

“We can also discourage raven activity in plover nesting areas by erecting bald eagle decoys and raven effigies to scare ravens away, but also remove ravens when necessary,” Mr. Press said. Fish and Wildlife permits the park to remove ravens lethally or through catch and release.