Thursday, September 25, 2014

The mystery of the Ashy storm-petrel

The records kept by egg collectors have been a valuable source of information about breeding birds on the Channel Islands. One such account from 1903 indicates that the ashy storm petrel nested on Catalina Island. But nobody has been able to find one since.

Until the summer of 2014, when biologists with the Catalina Island Conservancy and the California Institute of Environmental Studies found six nests on Ship Rock. They believe that there are even more Ashy storm petrels breeding on Catalina -- perhaps as many as fifty pairs.

The Ashy storm petrel lives year-round in the northern Pacific, ranging from Mendocino to Baja California. There are only about 10,000 birds, half of which nest on islands that are included in the Channel Islands National Park. The birds nest most frequently on islands or nearby rocks that are free of terrestrial mammalian predators, like rats.

How could the Catalina birds have gone unnoticed for so long? Well, Ashy storm petrels are easy to miss. First, they're not very big -- only about eight inches tall and about 1.3 ounces. That's about the size of a super-skinny American robin. And, like other storm petrels, they're nocturnal, flying to and from their nests under cover of darkness. Lastly, they prefer to nest in locations where it's hard for predators -- foxes, owls, and introduced rats -- to get to their nests. Perhaps it's not so surprising that they've been a mystery for so long.

You can read the LA Times story here.
Read more about Ashy storm-petrels in general and Channel Islands National Park populations.

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