Where Have All the Shorebirds Gone?
Where Have All the Shorebirds Gone?
Visiting Elsie Roemer Bird Sanctuary at Crown Beach last week, I noticed a lonely looking flock of about six marbled godwits, large cinnamon-colored shorebirds, resting with their heads tucked into their backs during a high tide.
This is quite a change from a month or two ago when the marsh was teaming with shorebirds of all sizes, roaming the mudflats at low tide or clustering at the Bay’s edge at high tide.
Their aerial displays were exciting as they rose in large groups and flashed from light, to dark, and light again as they flew in tight formations designed to evade predators.
Throughout the Bay about one million shorebirds gather in spring, some spent the winter here and some migrated from as far south as southern Chile.
San Francisco Bay is a spot of Hemispheric Importance (per the Western Hemispheric Shorebird Reserve Network) as shorebirds gather here for their spring migration as well as staying here for the winter. You may have noticed how quiet it is without their constant murmuring and staccato calls. So where did they go and when will they return?
In spring, the lengthening days cue shorebirds to prepare for migration and breeding. Surprisingly, the smallest of the shorebirds, Least Sandpipers and Western Sandpipers, make some of the longest journeys. They gather here and fly north along the Pacific Flyway — one of five “bird highways” across the U.S..
En masse they stop at the Copper River Delta in Alaska. The whole population of Least and
Western Sandpipers, along with hundreds of thousands of other shorebirds, geese, and some ducks, feast and rest, creating quite a spectacle. It also puts their whole species at risk, with all of them in one spot, should a terrible disaster befall that area.
Fueled up, the sandpipers then have the energy to continue their journey further north to the northern edge of Alaska where they nest and raise their young in the tundra.
Arctic summers provide shorebirds with ideal conditions for successfully raising their one batch of chicks. Abundant insect life provides food for the growing young. Nearly 24 hours of daylight in the “Land of the Midnight Sun” means the buffet is available 24/7.
The mostly uninhabited tundra gives the birds plenty of area for choosing their nest sites. The male sandpiper selects several sites to make a “scrape” where he flattens down the tundra grass with his body.
He then guides his mate to these sites and she selects the one she likes best (the original “open concept” floor plan!) and flattens it down some more and adds a few dried grasses and willow leaves and lichen to create a cup-on-the-ground about 2.5” wide and 2.5” deep.
They mate and she lays 2-4 well-camouflaged, densely-spotted eggs which they take turns incubating for about three weeks. The female will abandon the nest sometimes soon after the eggs hatch, or sometimes before, leaving the male to shepherd the self-sufficient young until they can fly a few weeks later.
The female needs to replenish her energy before her long migration south after producing those eggs in her tiny body.
The migration journey south is accomplished in stages, much like the ending of a party. The adults leave the nesting grounds first, likely sensing the shortening hours of daylight. The young leave a few weeks after the adults, guided by instinct and their own internal compasses.
Those that have escaped predation by larger birds and found sufficient food now have a chance to head to southern wintering grounds, often stopping or staying in San Francisco Bay for its abundant food resources. We should start seeing larger groups of shorebirds mid-August.
Shorebirds are endangered by climate change, with the potential for sea-level rise to reduce shallow-water, intertidal habitat needed to feed in their wintering grounds and nest and feed in Arctic nesting areas.
They are also at risk for pollution, especially since they travel through many coastal countries that don’t have the protections we currently enjoy in the U.S. Oil spills and other toxins can also affect them.
They’re just one of many “animals without borders” that need our help as advocates for a livable environment for ourselves as well as the wildlife with which we share our world.
Find out how you can volunteer or support efforts to help birds at www.goldengateaudubon.org.
Sharol Nelson-Embry is the retired Supervising Naturalist at the Crab Cove Visitor Center, EBRPD. She currently volunteers with the Golden Gate Audubon Society. Sharol also started cocoacase.com which features “bird friendly” chocolate.