From the August 2011 edition of Bay Crossings
Every time I write this monthly column, I find that I have to dive deep into a whole new world of chemistry, species, habitat, geology and climate. I enjoy sharing a little bit of what I learn along the way.
Some of you know I’m a novice birder, having become captivated with diving ducks while helping Golden Gate Audubon Society with its Christmas bird count out on the Bay. I love to see the fancy patterns of buffleheads and common goldeneyes and have enjoyed watching the western grebes on the central Bay into the spring. This July, however, I was struck by the sight of birds I had never noticed before.
Out on the Baykeeper boat last month, I spied about a dozen common murres, floating and diving in the deep water channel between the Golden Gate and Raccoon Strait. Looking a bit like (but unrelated to) penguins, these are the black and white beauties that grace rocky coastal headlands during the nesting season that runs from March through July.
These seabirds winter on the open ocean, foraging for small fish along the edge of the Continental Shelf near the Farallon Islands. In California, the major breeding colonies, or loomeries, are on the Farallon Islands, Pt. Reyes headlands and Devil’s Slide Rock.
Common murres are elegant and striking; Baykeeper volunteer and avian ecologist Bridget Gruel says she thinks of them as the Sophia Loren of birds. Born in a fancy blue or green speckled egg on a rocky cliff, common murres lead an adventurous life right from the start. The parents, who have only one chick at a time, memorize the pattern on their single egg and take turns incubating it. About 20 days after hatching, long before it can even fly, the chick will leap from its ledge into the water far below—sometimes from as high as 1,500 feet!
Over the next two weeks, the chick learns from the adult male how to swim and forage and, eventually, (unlike penguins) how to fly. Murres are adept swimmers, diving regularly to 200 feet—and occasionally more than 500 feet—in pursuit of juvenile rockfish, anchovies, smelt and squid that are small enough to be swallowed by the murre chicks.
The California populations of common murres had seen a severe decline due to commercial egging, oil spills and overfishing. After nearly 40 years of studying common murres on the Farallon Islands, however, PRBO Conservation Science reported that 2010 proved to be a robust year for common murres. A good year for rockfish reproduction seems to have translated into breeding success by the murres. Hopefully, common murres are making a true comeback—though the effects of climate change on ocean temperature and forage fish may be a steep hurdle.
If you’re lucky, you might see common murres at Point Reyes, Devil’s Slide Rock or even on the water, following schools of rockfish and anchovies into San Francisco Bay. But be sure to stay back at least 300 yards, whether on kayak, sailboat or foot, to keep from stressing this recovering species.
Photo courtesy of 1000birds.com