Western Snowy Plovers (Part III): Nesting Sites

Part III – Nesting and Wintering

Western Snowy Plovers (WSPs) are colonial nesters, up to 246 birds nesting in close proximity. Each nest is a bare scrape in beach sand, occasionally adorned with debris, twigs and pebbles. It might, but need not, have sparse vegetation nearby. The male often makes 1-2 false scrapes nearby. Three (occasionally two) eggs are laid, buff with black marks. Both parents incubate the eggs for 27-28 days. Hatchlings are precocial – the relatively long incubation period allows them to be born downy, mobile, ready to follow their parents and find their own food.  In about a month they’re full size and able to fly.

Of the estimated 50 California nesting sites used in 1970, about half are used today. In 1949, the last active nest of a Snowy Plover on L.A. County beaches was reported at Manhattan Beach. There have been no documented cases of a Snowy Plover nesting within the county since then, although no systematic survey of suitable county beaches was done between 1970 and the mid 2000s. Kiff & Nakamura (1978) held that they “probably nested at Malibu Lagoon until the 1960s when increased human use of the area displaced the birds,” but provided no supporting evidence.

As part of the ongoing PRBO study, nestlings are banded each year. Each location/year has a unique band pattern. Currently, 13 colors are used on four bands, two per leg. NO:WW means: Left leg Light Brown above Orange, Right leg White above White. A nestling was banded with this particular pattern at Vandenberg Air Force Base in Summer 2009. We first found it in the Surfrider flock on Oct. 25, 2009 (see photo at top) and last saw it there on Dec. 25, 2011.

As the result of the first Winter Window Census in January, 2001, we found that WSPs in Los Angeles County were concentrated into seven locations, which were their winter roosting sites; outside those locations they were extremely uncommon. We found:

Surfrider Beach

Birds in 2001 at Surfrider (2) and Cabrillo (0), although seen in good numbers the previous day, were low on count day due to poor weather conditions.

To my knowledge, no one knew that Snowies stayed so close to their winter roosts. All later censuses proved that 2001 was not an anomaly. With few exceptions, the birds are just not found more than a few hundred yards – usually much less than that – from their roosting sites. Their seven roosting sites, with one exception, have not changed since then. The exception was on Dockweiler, where the roost at the foot of the hang-gliding slope disappeared when a site about ¼ mile north appeared.