Flightless Cormorant - Phalacrocorax harrisi

Flightless Cormorant - Phalacrocorax harrisi.

IUCN STATUS CATEGORY Vulnerable

HABITAT Breeds along rocky shoreline, in small colonies which are not easily accessible. Restricted to within 100m of coastline while swimming. Its range coincides with the coldest, richest waters in the Galapagos.

GEOGRAPHICAL SPREAD Restricted to 370km of coastline on Fernandina and Isabela in the Galapagos Islands, Ecuador. Movements between Fernandina and Isabela are very rare.

CURRENT POPULATION In 1994, there were 700 to 800 pairs in 112 or more colonies. The population is generally around 1,000 individuals, but dips in El Niño years (a 50 per cent decline occurred in 1983) recovering within a few breeding seasons.

SIZE 89 to 100cm. The male is larger than the female.

WEIGHT 2.5 to 4.0kg.

AVERAGE LIFE EXPECTANCY Unknown.

NORMAL DIET Benthic fishes, eels and octopuses.

NORMAL LIFESTYLE The species has a high recovery rate which may be due to some pairs nesting twice a year. Nests on sheltered boulder beaches, rocks and lagoons. The cormorants are attached to their breeding grounds, rarely found more than 1km away. Nesting colonies consist of small breeding groups of up to 12 pairs. Two or three whitish eggs are laid in a bulky nest of seaweed built just above the high-water mark. Feeding is mainly by pursuit diving. Numbers of this species fluctuate regularly due to the effects of El Niño events. On average, El Niño occurs every 12.3 years, although the 1982-83 event was the most severe for around 100 years. El Niño is caused by a failing of the trade winds resulting in an increase in sea temperature of about 4.3°C along with an increase in sea levels and precipitation.

PREVIOUS GEOGRAPHICAL SPREAD As present.

REASONS FOR DECLINE Before their elimination from the coastline of Isabela, feral dogs were considered a threat to the cormorants on this island.

CURRENT THREATS The cormorant is flightless and shows no dispersal tendencies, rendering it extremely vulnerable to human disturbance or oil pollution, and more recently Japanese sea-cucumber fisheries. Although the number of visitors to the Galapagos has increased, the habitat of the species is inhospitable to tourists. Fishing with nets around the Galapagos is a serious threat, as birds can become caught in nets, or have a substantial reduction in the available food source.

CONSERVATION PROJECTS The Charles Darwin Research Station has regularly monitored the individual populations of this species since 1977. In view of the potential threats from feral animals and fishing interests, regular monitoring of this small, endemic species should continue.

SPECIAL FEATURES The breastbone or sternum of the cormorant has lost the keel which in most birds serves as attachment for flight muscles. This is the only flightless member of the cormorant family.

REFERENCES

Collar, N.J., Crosby, M.J. and Stattersfield, A.J. 1994. Birds to Watch 2. The World List ofThreatened Birds. BirdLife International: Cambridge.

Harcourt, S.A. 1980. Report on a Census of the Flightless Cormorant and Galápagos Penguin. Noticias de Galapagos. 32: 7-11.

Hoyo, J.d., Elliot, A. and Sargatal, J. 1992. Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona. 640pp.

Rosenberg, D.K., Harcourt, S.A. 1987. Population Sizes and Potential Conservation Problems of the Endemic Galápagos Penguin and Flightless Cormorant. Noticias de Galapagos. 45: 24-25.

Valle, C.A. 1986. Status of the Galápagos Penguin and Flightless Cormorant Populations in 1985. Noticias de Galapagos. 43: 16-17.

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