The Guanay Cormorant Phalacrocorax bougainvillii

From historical times the guanay cormorant has been the dominant avian species in the ecosystem of the Peruvian Coastal Current, in terms of numbers and consumption of marine resources. The number of guanay cormorants in 1954 was estimated in 22 millions of birds only in the central and northern coast of Peru. Current numbers of this species do not exceed 3 millions of birds (Goya 2001). Competition with the commercial fisheries and long-term changes in marine productivity have been the main cause for this decline. Over 70 species of pelagic and demersal fish and some species of squid have been found in its diet (Jahncke and Goya 1998), showing a high flexibility on their feeding habits. However, anchovies, mote sculpins and silversides accounts for 87% of the overall number of items. They forage during daylight in large flocks, but occasionally small groups can also be observed. Mean maximum dive depth is 34 m, but the deepest dive recorded was 74 m (Zavalaga and Paredes 1999). Duration of feeding trips are highly variable, but in Punta San Juan during the summer 1994-95 these trips averaged 6 hours. Breeding can be seasonal in some localities but can extend for most part of the year in others. They nest in mainly in flat areas in islands and fenced headlands. Main breeding sites in Peru are Isla Mazorca, Islas Chinchas, Isla Macabi, Isla La Vieja and Punta San Juan.

Main threats include overfishing of Peruvian anchovies, poaching of adults for food and disturbance in their nesting sites.