Enticed by Sounds, Bermuda Petrels Gain New Nest Sites

Mark Reaves

In the Spring 2004 issue of BirdScope, Mark Reaves reported on a trip to Green Island in Bermuda to record the eerie moaning vocalizations of cahows, or Bermuda Petrels. At the time, only 70 breeding pairs remained in the world and 65 juveniles were believed to be living at sea.

Mark sat on Green Island in the dark, recording cahows in low-flying courtship displays just inches over his head. Using a technique pioneered by Stephen Kress, director of Audubon's Seabird Restoration Program, the recordings would be broadcast in an attempt to attract cahows to artificial nesting burrows on predator-free islands. The new chambers were also safer because they were placed on higher ground than where waves from Hurricane Fabian washed away natural burrows in 2003.

The strategy appears to be working. Three new cahow pairs have settled into burrows on Nonsuch Island. Two of the burrows were next to speakers broadcasting the courtship calls, according to Jeremy Madeiros, conservation officer for Bermuda's Department of Conservation Services.

Remarkably, the third burrow was occupied by a pair that had lost its original burrow during Hurricane Fabian. Biologists picked up the pair from rubble where the original nest had been destroyed and released them together into the new burrow.

"This is all fantastic news," Stephen Kress said. "The idea of actually picking up adults and moving them to a new burrow near the speakers is remarkable and shows real innovation."

Jeremy Madeiros reported that this year the cahow population has almost recovered from the loss of burrows during Hurricane Fabian, with a total of 6 newly established pairs and 71 active burrows with an egg (a record high). Thirty-five chicks fledged in 2005, compared with twenty-nine last year. Twenty-one of these chicks were translocated to Nonsuch Island, and all fledged. Researchers hope that some will return to the island to found a new colony.

"It was very rewarding to be watching the translocated chicks fledge from the tops of trees that they had climbed, or from forest clearings," Jeremy said. "One even fledged from the top of an artificial tropicbird nest that contained an adult tropicbird incubating an egg."

For permission to reprint all or part of this article, please contact Laura Erickson, editor, Cornell Lab of Ornithology, 159 Sapsucker Woods Rd., Ithaca, NY, 14850. Phone: (607) 254-1114. email: lle24@cornell.edu