Perhaps the world’s most storied seabird, Bermuda Petrel (Pterodroma cahow)—or Cahow, as it is called on Bermuda—was little more than legend until its rediscovery and description in the twentieth century, more than 300 years after it had vanished from human experience.(For a comprehensive overview of Bermuda Petrel ecology, check out their species account at Neotropical Birds Online.)
The Search & Rediscovery
At last, in January 1951, a scientific expedition was organized to search for the bird, led by Louis S. Mowbray (son of the 1906 discoverer) and by Robert Cushman Murphy and his wife, Grace E. B. Murphy. During a careful survey of the islets around Castle Harbor, they found seven nesting pairs of Bermuda Petrel, and the news of the discovery quickly spread around the world through the news media, with rare fanfare, at least for a seabird.
Accompanying Mowbray and the Murphys on the expedition was a local Bermudian schoolboy, David B. Wingate, who was present when the first petrel was found, on 28 January 1951. Just two years later, the young Wingate acquired a specimen of Bermuda Petrel from an antique dealer; it proved to be from the 1800s, from the collection of John Tavernier Bartram, a naturalist who searched for the species without realizing he had a specimen in his possession. After graduating from Cornell University in 1957, Wingate returned to Bermuda to work on petrel conservation, under the auspices of the Bermuda Aquarium. He would become Bermuda’s Conservation Officer and the birds’ outspoken champion over the next five decades.
Conservation Risks and Successes
During that time, the tiny population of petrels was nearly lost again, first to terrible nest-site competition with another seabird, the White-tailed Tropicbird (Phaethon lepturus), first noted in 1951, then to egg-shell thinning caused by DDT. Wingate reduced, then eliminated the tropicbird problem by constructing tropicbird-excluding baffles at the entrances of active petrel burrows, which admit the petrels but keep out the larger-bodied tropicbirds. A successful, and ongoing campaign has also been carried out to supply tropicbirds with artificial nest “Igloos,” placed away from petrel nesting areas. The egg-shell thinning problem improved greatly following the banning of DDT in the early 1970s. In addition, a shortage of suitable deep nest burrows for the petrels on the rocky original nesting islands, which have little or no soil for them to burrow into, was solved by digging and constructing artificial concrete burrows, a program that continues to this day. These burrows have been so successful that they are now used by over 80% of the nesting population, enabling the petrel population to grow at an increasing rate.
In recent decades, there has been increasing overwashing and erosion of the original small nesting islands, which average only 0.5 to 1.0 acre in size each, during frequent episodes of hurricane surge. This has resulted in petrel mortality and the destruction of nest burrows, posing an urgent problem for Bermuda’s new Senior terrestrial conservation officer, Jeremy Madeiros, who has managed the Cahow Recovery Program since David Wingate’s retirement in 2000. Thus, Madeiros commenced a program in 2002 of translocating, or moving near-fledged young petrels from the original vulnerable nesting islands to artificial burrows on higher ground, on the nearby much larger Nonsuch Island Nature Reserve, which Wingate and Madeiros have reforested to its precolonial state over the past 56 years. By doing this, the fledgling petrels imprinted on the new site rather than the original tiny sub-optimal islands, which did not offer sufficient area for the species to completely recover. These translocated petrels returned when mature after several years at sea, and began nesting on Nonsuch in 2009 for the first time since the 1620s. As of early 2017, with a total of nearly 120 nesting pairs of Bermuda Petrel, there is guarded optimism for the survival of this striking seabird.
About the Site
The CahowCam is nestled in the side of a dome-shaped, manmade burrow constructed by the Bermuda Department of Environment and Natural Resources (DENR) on Nonsuch Island. These burrows are part of a larger translocation project that is essential to the long-term survival of the Bermuda Cahow, whereby juveniles from smaller, low-lying islets are translocated to Nonsuch Island, where there is ample habitat out of the reach of hurricanes and heavy surf. As of 2016, there are two translocated colonies on Nonsuch Island, and the DENR continues to work at establishing additional safe nesting spots for cahows to breed.
About the Petrels
Thanks to the efforts of the Bermuda DENR, both of the petrels nesting in the Cahow Cam burrow have been banded, and their individual histories have been recorded through prior nesting seasons. The breeding pair of Bermuda Petrels, or Cahows, that nest in the cam burrow (#R831) on Nonsuch Island, were both translocated in May 2006 as two-thirds fledged chicks from two separate nesting islets to artificial burrows on the larger and more elevated Nonsuch Island Nature Reserve. Once translocated, the chicks were hand-fed daily and monitored until they fledged out to sea. Both of our birds in the 831 nest then stayed out at sea for three years until they matured, and returned to pair up together in this nest in 2009. They have returned every year since to breed. Cahows produce only one egg each year, and are faithful partners, generally pairing up with the same mate for life, which may be over 30 years.
After colonizing this burrow in 2009, E0212 (the male) and E0197 (the female) nested unsuccessfully from 2010 through 2013. From 2014 to 2016, they were successful in fledging a chick each year, and we are hopeful for continued success this year.
The pair returned to the island in mid-November to court and mate, then disappeared out to sea for the month of December. On January 11, the female returned, and within an hour or so of arriving she laid a single egg that will be the singular focus of the pair’s efforts for the next 5-6 months (watch highlight). In the next 24-48 hours, the male should return to take over incubation duties for the next month while the female heads out to sea, and hatch won’t be for another 52-55 days—likely around the end of the first week of March. If the chick hatches successfully, fledging should occur around the first week of June.
About the Team
Multiple groups are working to raising awareness about the endangered Bermuda Cahow through the live CahowCam. LookBermuda and the Nonsuch Expeditions have collaborated with the Bermuda DENR since 2011 to bring the live cam to life, and have streamed live footage from burrows on Nonsuch since 2013. Continued support from Terrestrial Conservation Officer Jeremy Madeiros has been essential in arranging visits to Nonsuch, learning about cahow conservation, and the opportunity to share the ongoing work needed to safeguard the cahow’s future. Finally, a special thanks to the Government of Bermuda for prioritizing the ongoing conservation of this national treasure.