Birds and Mammals
|Masked Booby at La Jolla
The new year (2002) started with a surprise for birders when a Masked Booby (Sula dactylatra), the first ever seen on the shore of San Diego County, showed up at La Jolla, roosting on the cliffs with the many cormorants and Brown Pelicans. The Masked Booby has been conclusively identified in California only about 15 times previously, on all but three occasions far out to sea. One in January and February 1997, though, remained for a month at Point Mugu, Ventura County.
Boobies are tropical ocean birds, nesting on islands. They are related to pelicans and cormorants but are easily recognized by their unique shape. For people unfamiliar with boobies, though, the five species in the North Pacific Ocean can be difficult to identify, especially because the young birds take several years to attain the adult colors of the plumage, bill, and feet. In fact, it was only in 1998 that Robert L. Pitman and Joseph R. Jehl published their discovery that the Masked Booby actually consists of two species, the Masked Booby (Sula dactylatra) and Nazca Booby (Sula granti). Differing mainly in bill color, the two nest on some of the same islands, such as Clipperton Atoll and San Benedicto in the Revillagigedo archipelago. The booby at La Jolla is easily identified as the Masked by its dull greenish bill surrounded by a mask of bare blackish skin and its black and white plumage. Some blackish feathering on the head and back suggests it is not quite yet fully adult.
Not only the Masked but the Red-footed and Brown Boobies as well have become far more frequent in California in the past 15 years. There are now over 12 well-supported identifications of the Red-footed and over 50 of the Brown, in addition to the 15 of the Masked. Previously, these birds were almost unknown this far north. Why are these tropical ocean birds showing up more often? Could it be a symptom of global warming? The composition of the birdlife along the California coast has changed dramatically in recent years, with steep declines in some formerly common species like the Sooty Shearwater and Cassin's Auklets while some rare birds, like the boobies, increase.
Last seen on January 10, 2002.
Text by Philip Unitt, Curator, Birds and Mammals Department