Inside its nest box (used by PRBO and USFWS to monitor this seabird population), a Cassin's Auklet with its seasonally early egg.
Itís early March, a transitional season for both wildlife and PRBO biologists on Southeast Farallon Island. Weíre systematically visiting all the Cassinís Auklet study plots. Our first challenge is to locate the 50 or so numbered nest boxes that we use to monitor this population. Our second challenge is to find an auklet present. This early in the year, we actually aim to record dates when no birds are found in the plots. That way, if a nesting auklet is present the next time, we can estimate when it arrived in the colony. Because Cassinís Auklets feed on plankton (krill), their breeding is a good indicator of conditions in the marine food web.
We step carefully in thick vegetation to avoid the natural burrows in the soil. After locating the first study plot, we check all the boxes. The procedure is the same at each: foot in hole to block the entrance to the box in case thereís a bird to find inside; remove rock from lid; peek under lid; record result. First study plotónada. Second study plotónil. Third study plotónothing. By now my expectation of finding a bird is low.
Then we make our way to the last plotówhere we find a bird not only present but incubating its egg! This is the earliest that PRBO has ever recorded a Cassinís Auklet breeding in one of our study plotsóMarch 2nd.
Forty years of monitoring Farallon seabirds have shown us that ďearlyĒ often equates with high reproductive success. Expectations for Cassinís Auklets in 2011 are suddenly much greater!
Ryan Berger is a Farallon Biologist in PRBOís California Current Group.