A cagarra (Calonectris diomedea) é uma ave marinha de grande porte, conhecida pelas suas asas longas e esguias e pelo seu voo gracioso. Mede cerca de 45-56 cm de comprimento, com uma envergadura de asa de aproximadamente 112-126 cm, e pesa cerca de 700-800 gramas. A plumagem da cagarra é essencialmente castanha-acinzentada nas partes superiores e branca nas partes inferiores. As asas são longas e pontiagudas, com a parte superior castanha-acinzentada e a parte inferior branca com bordos escuros. A cauda é relativamente curta e escura, enquanto a cabeça tem um gorro acinzentado com a testa e a garganta brancas. Esta cagarra é conhecida pelo seu voo poderoso e planado sobre o oceano aberto, onde passa a maior parte da sua vida. Durante a época de reprodução, a cagarra nidifica em tocas ou fendas em falésias e ilhas do Mediterrâneo e do Atlântico Norte.
Habitats e distribuição
Cory's Shearwater primarily inhabits open ocean environments, favoring warm-temperate and subtropical waters. During the breeding season, it is commonly found on remote islands and coastal cliffs in the Mediterranean Sea, the Canary Islands, and the Azores. The bird constructs its nests in burrows or crevices, often on steep, inaccessible cliffs where predator presence is minimal. Outside the breeding season, Cory's Shearwater exhibits pelagic behavior, spending most of its life at sea. Its non-breeding range extends across the North Atlantic Ocean, with wandering individuals occasionally reaching the coasts of North America and West Africa. This wide-ranging seabird is highly adapted to life on the open ocean, foraging over vast distances and relying on the marine environment for its primary food sources, which include fish and squid.
Comportamentos e reprodução
Cory's Shearwater exhibits monogamous mating habits, often forming long-term pair bonds that can last for several breeding seasons. These seabirds nest colonially, predominantly on islands in the Mediterranean and the Atlantic, selecting crevices, burrows, or under rocks for their nests. Their social structure is relatively loose outside the breeding season, but during nesting, individuals display strong site fidelity, returning to the same location each year. Reproduction begins with elaborate courtship displays that include synchronized flight patterns and vocalizations. Mated pairs share the responsibility of incubating a single egg, with shifts that can last several days. Both parents take turns feeding the chick regurgitated fish and squid, ensuring it reaches fledging age. Cory's Shearwater adopts a “slow” life history strategy, as reflected in their relatively late sexual maturity and low reproductive rate, which is offset by their longer lifespan.
Dieta
A cagarra alimenta-se principalmente de peixes, lulas e crustáceos. Forrageia no mar, muitas vezes mergulhando e usando as asas para nadar debaixo de água e apanhar as suas presas.
Cores
Cinzento, branco, preto, castanho
Factos divertidos
Long-Distance Migrant: Cory's shearwater undertakes extensive migrations, traveling thousands of kilometers between breeding and feeding grounds.
Social Birds: They are often seen in large flocks, especially during migration and while feeding.
Nocturnal on Land: During the breeding season, Cory's shearwater is mostly active at night to avoid predators.
Distinctive Call: Known for their eerie, wailing calls, which can be heard especially during the breeding season at their colonies.
Estado de conservação e esforços
Cory's Shearwater (Calonectris diomedea) is currently considered of Least Concern according to the IUCN Red List, yet its population is experiencing certain pressures. The population trend is generally stable, although there are localized declines in certain breeding colonies. Primary threats include habitat destruction, pollution, bycatch in fisheries, and invasive species like rats and feral cats that prey on eggs and chicks. Conservation efforts for Cory's Shearwater involve a combination of habitat protection, bycatch mitigation, and invasive species eradication. Specific measures include the protection of breeding sites through the designation of marine protected areas and the implementation of biosecurity protocols to prevent the introduction of non-native predators. Additionally, conservationists are working with the fishing industry to adopt bird-friendly practices and reduce bycatch. These efforts aim to stabilize and potentially increase the population of this important seabird.
Galeria
