Thứ Bảy, 23 tháng 2, 2013

Northern gannet

Morus bassanus

Photo by Andreas Trepte (Wikipedia)

Common name:
northern gannet (en); ganso-patola (pt); fou de Bassan (fr); alcatraz común (es); basstölpel (de)

Taxonomy:
Order Pelecaniformes
Family Sulidae

Range:
The northern gannet is found in the northern Atlantic, from Greenland south along the coasts of Europe, north-western Africa and North America down to Cuba and Senegal.

Size:
These birds are 80-110 cm long and have a wingspan of 165-190 cm. They weigh 2,2-3,6 kg.

Habitat:
The northern gannet is found in coastal and marine waters, never very far from the coast. They breed in steep cliffs or uninhabited offshore islands.

Diet:
They feed on pelagic shoaling fish, which they catch by plunge-diving from considerable heights. They often feed in association with predatory fish and cetaceans, such bluefish and dolphins. Their main prey are mackerel and herring, but also capelin, coalfish, cod, whiting, haddock, sprat, pilchard, garfish, sandlance, sandeel, smelt, menhaden and flounder, typically smaller than 30 cm. They can also eat some squids and shrimps.

Breeding:
Northern gannets breed in March-September. They are monogamous and pair for life. The nest is a mound of seaweed, feathers and plant materials, placed in a rocky cliff or island always near the ocean. The female lays a single pale blue-green chalky egg, which is incubated by both parents for 42-46 days. The chicks fledge 3 months after hatching. Each pair raises a single chick per season, which will reach sexual maturity after 3 years.

Conservation:
IUCN status - LC (Least Concern)
This species has an extremely large breeding range and the global population is estimated at 950.000-1.200.000 individuals. Although they suffer some mortality from entanglement in nets and other fishing gear, the population in North America in known to be increasing at a rate of 3-3,5% per year, while the population is Europe seems to be stable.

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