One year of plover habitat help

By Corny Foster

If you are walking the north end of Crissy Field beach in the Presidio, you can easily mistake a Western Snowy Plover for one more ripple of sand. Camouflage helps the plovers evade predators. It is also the reason that few people know the birds are there until they almost step on them!

Luckily, there are some people who are highly aware of the plovers – Golden Gate Bird Alliance and National Park Service volunteers who spend one morning each month grooming the Crissy Field beach to maintain suitable habitat for the birds.

We recently reached the one-year anniversary of the Crissy Field volunteer program. Over the past year, volunteers put in 105 hours removing invasive weeds and collecting 36 buckets of trash – all aimed at ensuring a hospitable home for the sparrow-sized plovers.

The Western Snowy Plover — the Pacific Coast sub-species of the Snowy Plover — inhabits coastal areas from Washington State to Baja California. There are well-publicized programs to protect the plovers’ nesting beaches, such as those at Point Reyes and the Monterey Peninsula.

But the Bay Area’s wide sandy beaches are also important to the plovers as an overwintering site, where between July and May they build up energy reserves for migration and breeding.

The first person to identify these small birds was Lt. William P. Trowbridge, who supervised the construction of the San Francisco Tide Gauge near the Golden Gate in 1854. Trowbridge was a West Point graduate and an accomplished naturalist who collected biological specimens and sent them east to be examined and included in museum collections.

Of the many species he collected, some proved to be new to the body of scientific knowledge.  One such species was the Snowy Plover (Charadrius nivosus), which Trowbridge collected on May 8, 1854 from the shoreline dunes of the Presidio.

Habitat loss and degradation due to development, beach recreation, and non-native vegetation have contributed to a decline in the Western Snowy Plover population, which in March 1993 was listed as “threatened” under the Endangered Species Act.  Up to 100 of the estimated 2,300 birds remaining on the Pacific Coast overwinter in San Francisco on Ocean and Crissy Field beaches in the Golden Gate National Recreation Area (GGNRA).

At GGNRA, use of these popular beaches by patrol vehicles, equestrians, dogs, joggers, and kite flyers can disturb the plovers, cause them to expend excessive energy fleeing, and make them more visible to avian predators. Despite the high levels of disturbance, Snowy Plovers return to the GGNRA every year, possibly because the beaches provide high quality prey or offer some of the only suitable habitat left in the region.  The GGNRA has established Protection Areas on both beaches, which require walking and other recreation to take place on the wet sand, and for dogs to be leashed.

Since March 2012, a small group of Audubon and park volunteers spend the second Monday of every month grooming the Crissy Field Wildlife Protection Area (WPA), removing trash and non-native vegetation such as sea rocket.  (And, of course, birding!)

For better or worse, the trash at Crissy WPA reflects many of the lives of Bay Area residents.  Cherished plastic Batman rings and GI Joes are lost in the sand and find their way to the volunteers’ buckets.  The plastic refuse of our modern civilization washes off the streets of San Francisco and into the volunteers’ buckets – pens, bottle caps, packing materials and candy wrappers. Plastic shotgun shells come down from the Delta after a day of duck hunting. It’s particularly important to collect fishing line and string of any sort that might tangle in the snowies’ legs and cause injury.

Since the volunteers have regularly been cleaning the beach, the average size of the plastic has dropped but new items constantly wash in. Native vegetation has expanded since it faces less competition from invasive species.

Under the shadow of the Golden Gate Bridge, the Crissy WPA is becoming a wonderful example of a natural beach on San Francisco Bay.  It hosts many native plants including sand verbena, beach evening primrose, beach bur, beach saltbush, coastal sagewort, beach morning glory, American beach grass and the endangered dune gilia.

And enjoying the beach as the seasons change are Snowy Plovers, Killdeer, Long-billed Curlews, Whimbrels, Willets, Least Sandpipers, Sanderlings, Western Gulls, Elegant Terns, Common Ravens and American Crows… well, you probably know the usual suspects for Bay Area beaches.  Occasionally something unusual goes by, like five Brant Geese and a Pomarine Jaeger!

The volunteers work from 10:00 a.m .to noon every second Monday of the month, meeting in front of the Warming Hut in the Presidio — rain or shine, snowies in residence or not.

If you love birds and love (or at least tolerate) picking up small pieces of plastic, please join the group. (The next work days will be on Monday June 10th and July 8th.)

And the next time you see a bit of Crissy Beach sand unexpectedly move, stop and watch a Snowy Plover foraging in the high tide wrack line.

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Corny Foster is a retired banker who spends much of her time volunteering with the GGNRA in the Presidio and Alcatraz, working with birds, native habitat restoration and historic garden preservation.  She leads the Monday work groups at Crissy WPA.