Cormorant Colony Adrift as Old Bay Bridge Comes Down

The Old Bay Bridge Is Coming Down, Leaving a 40-Year-Old Cormorant Colony Adrift

by Mark J. Rauzon on March 28, 2017  BayNature

….Back in the late 1800s before bridges spanned the Bay, several thousand double-crested cormorants nested on Lands End near Seal Rocks off the coast of San Francisco and on the Farallon Islands. The great ornithologist of the era, Robert Ridgway, described the Pacific Coast bird as a subspecies of the double-crested cormorant found throughout North America and he gave them their own moniker—the Farallon cormorant (P. a. albociliatus)….They were first documented nesting on the Bay and Richmond-San Rafael bridges in 1984, though bridge workers reportedly saw them 20 years earlier on the latter….

I began studying those double-crested cormorants under the Richmond-San Rafael Bridge with Point Reyes Bird Observatory (PRBO, now Point Blue Conservation Science) in 1988….

….All this changed on October 17, 1989, when the Loma Prieta earthquake cracked the Bay Bridge right above the colony (not the birds’ fault!). Although it took years of political wrangling to settle on a new bridge design that was acceptable to all parties, the resulting plan included an agreement to provide habitat replacement for the cormorants on the new bridge.

….Losing the unique cormorant bridge colony in the central Bay is the end of an era. Our urban cormorants are at a crossroads. …. Double-crested cormorants have colonized urban habitats and benefited from human manipulation of San Francisco Bay. Where many species are failing to survive, the cormorant is thriving. They deserve respect for their adaptive qualities and commiseration for their commuting lifestyle.  The next time you’re stuck on the bridge, watch for cormorants flying by; understandably, you might wish you could join them.

Mark Rauzon is a seabird biologist with extensive experience in restoration programs, detailed in his latest book Isles of Amnesia. He also teaches geography at Laney College, is a founding member of Friends of Sausal Creek, and is a Point Blue research associate