This is the season when the mudflats of San Francisco Bay swarm with southbound migrant shorebirds: willets, godwits, curlews, dowitchers, plovers, and, outnumbering all the rest, western sandpipers. In the late 1980s and early 1990s, scientists from the Point Reyes Bird Observatory (now PRBO Conservation Science) attempted to estimate the birds’ year-round numbers. For western sandpipers, they came up with average fall and winter counts of over 100,000 individuals and spring counts of over 500,000. The peak spring count exceeded 700,000. That’s a lot of avian biomass, even at nine-tenths of an ounce per bird.
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