Zino's petrel (Pterodroma madeira) or the freira, is a species of small seabird in the gadfly petrel genus, endemic to the island of Madeira. This long-winged petrel has a grey back and wings, with a dark "W" marking across the wings, and a grey upper tail. The undersides of the wings are blackish apart from a triangle of white at the front edge near the body, and the belly is white with grey flanks. It is very similar in appearance to the slightly larger Fea's petrel, and separating these two Macaronesian species at sea is very challenging. It was formerly considered to be a subspecies of the soft-plumaged petrel, P. mollis, but they are not closely related, and Zino's was raised to the status of a species because of differences in morphology, calls, breeding behaviour and mitochondrial DNA. It is one of Europe's most endangered seabirds, with breeding areas restricted to a few ledges high in the central mountains of Madeira. Zino's petrel nests in burrows which are visited only at night, when they give their haunting calls. The single white egg is incubated by both adults, one sitting during the day while the other feeds on fish and squid at sea. Eggs, chicks and adults have been subject to predation by introduced cats and rats, and in the past have been taken for food by local shepherds. Predator control, and other measures such as the removal of grazing animals that trample the burrows, have enabled the population to recover to 65–80 breeding pairs; the species remains listed as endangered on the IUCN Red List. However, conservation efforts had a major setback in August 2010 when fires killed three adults and 65 percent of the chicks. The population eventually recovered and was stable at 160 individuals by 2018.
Taxonomy The gadfly petrels in the genus Pterodroma are seabirds of temperate and tropical oceans. Many are little-known, and their often similar appearance have caused the taxonomy of the group to be rather fluid. The forms breeding in Macaronesia on Madeira, Bugio in the Desertas Islands, and in the Cape Verde archipelago were long considered to be subspecies of the Southern Hemisphere soft-plumaged petrel, P. mollis, but mitochondrial DNA analysis, and differences in size, vocalisations, breeding behaviour, showed that the northern birds are not closely related to P. mollis, and that the Bermuda petrel or Cahow may be the closest relative of the Macaronesian birds. Ornithologist George Sangster recommended establishing Zino's petrel on Madeira and Fea's petrel on the Desertas and Cape Verde as full species, and the species split was accepted by the Association of European Rarities Committees (AERC) in 2003. Nunn and Zino estimated that the two Macaronesian species diverged at the end of the Early Pleistocene, 850,000 years ago. An analysis of feather lice taken from Fea's petrels, Pterodroma feae deserti, from Bugio Island, and from Zino's petrels from the Madeiran mainland showed that there were marked differences between the two seabirds in terms of the parasites they carried, suggesting that they have long been isolated since lice can normally only be transferred through physical contact in the nest. The species on Zino's petrel are most similar to those of the Bermuda petrel, whereas Fea's petrel's lice are like those of Caribbean and Pacific Pterodroma species. This suggests that despite the close physical proximity of the two species of gadfly petrel found in the Madeiran archipelago, they may have arisen from separate colonisations of mainland Madeira and, later, the Desertas Islands. Although their reproductive isolation has allowed the separate evolutionary development of the two species, genetic evidence shows the three Macaronesian petrels are each other's closest relatives. The petrels breeding in the high central mountains of Madeira were first recorded in 1903 by German naturalist and priest Ernst Johann Schmitz, who failed to realise that they were different from the Fea's petrels he had seen in the Desertas. The species was formally described as a race of soft-plumaged petrel by Australian amateur ornithologist Gregory Mathews in 1934. Following the recognition of the Madeiran birds as a full species, they were named after the British ornithologist, Paul Alexander Zino, who was instrumental in their conservation during the latter half of the twentieth century. The genus name Pterodroma is derived from Greek πτερον, pteron, "a wing", and δρομος, dromos, "running", and refers to the bird's swift erratic flight. The specific madeira refers to the island on which it breeds. The Portuguese name Freira means "nun"; the inhabitants of Curral das Freiras (Nun's Valley) near the breeding site claimed that the nocturnal wailing of the petrels in the breeding season were the calls of the suffering souls of the nuns. The sisters had taken refuge in the valley from attacks on the island by French pirates in 1566 that lasted for 15 days. Pterodroma petrel remains dated between 60,000 and 25,000 years BP were found in two cave sites in Gibraltar. They consist of a more abundant form similar in size to Zino's, and a larger, less common type. It is uncertain whether they represent the site of a former breeding colony, or are the result of a seabird wreck in which storms blow birds inland. They do suggest, however, that members of the genus were formerly more widespread.
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