Bermuda petrel

The Bermuda petrel (Pterodroma cahow) is a gadfly petrel. Commonly known in Bermuda as the cahow, a name derived from its eerie cries, this nocturnal ground-nesting seabird is the national bird of Bermuda and can be found on Bermudian money. It is the second rarest seabird on the planet and a symbol of hope for nature conservation. They are known for their medium-sized body and long wings. The Bermuda petrel has a greyish-black crown and collar, dark grey upper-wings and tail, white upper-tail coverts and white under-wings edged with black, and the underparts are completely white. For 300 years, it was thought to be extinct. The dramatic rediscovery in 1951 of eighteen nesting pairs made this a 'Lazarus species', that is, a species found to be alive after having been considered extinct. This has inspired a book and two documentary films. A national programme to preserve the bird and restore the species has helped increase its numbers, but scientists are still working to enlarge its nesting habitat on the restored Nonsuch Island. Cahows typically eat small fish, squid and shrimp-like crustaceans. They also predominantly feed in colder waters. Geolocator studies carried out between 2009 and 2011 confirmed that they primarily forage in two widely separated locations during the non-breeding season (July to October), between Bermuda, Nova Scotia and North Carolina, and to the north and northwest of the Azores archipelago. Special glands in their tube-like nostrils allow them to ingest seawater. These glands filter out the salt and expel it through sneezing. Initially they were superabundant throughout the archipelago, but because of habitat degradation and invasion of mammals, the bird's suitable nesting areas have dwindled to four islets in Castle Harbor, Bermuda, in the warm waters of the Gulf Stream, some 650 miles east of North Carolina. The cahow is a slow breeder, but excellent flier. It visits land only to nest and spends most its adult life on the open seas ranging from the North Atlantic coastal United States and Canada to waters off western Europe. After 3–4 years at sea, males return to breeding islands to create nests. Breeding season takes place during January and June. They nest in underground burrows and only the ones that can be in complete darkness are chosen. Females return after 4–6 years at open sea looking for a mate; the females lay one egg per season. 40% to 50% fail to hatch. Eggs are incubated by both parents and take 53–55 days to hatch. Hatching occurs between May and June. Cahows mate for life and typically return to the same nest each year. The Spanish sailors of the 1500s used Bermuda and its surrounding islands as a waypoint for their raids against the Inca and other civilizations. At that time, cahows were abundant and formed dense, noisy colonies. These sailors, as Diego Ramirez writes in 1603, would take up to 400 birds a night for food. In addition to eating birds, conquistadors brought hogs to the island to sustain themselves over their voyage. These hogs decimated the ground-nesting cahow, rooting up their burrows, eating eggs, chicks and adults and disrupting their breeding cycle. Following the Spanish arrival in Bermuda, the English ship Sea Venture was wrecked on the island in 1609. Those men that were shipwrecked culled the fattest individual petrels and harvested their eggs in abundance, especially in January when other food sources were diminished. This shipwreck led directly to the settlement of the island by the English in 1612. Bermuda's colonization by the English introduced species like rats, cats and dogs, and mass killings of the birds for food by these early colonists devastated their numbers. The remaining cahow population also decreased due to widespread burning of vegetation and deforestation by the settlers during the first 20 years of settlement. Despite being protected by one of the world's earliest conservation decrees, the governor's proclamation 'against the spoyle and havocke of the Cohowes', the birds were thought to have become extinct by the 1620s.