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Range DescriptionPhalacrocorax bougainvilliorum is found along the Pacific coast of Peru and northern Chile. A small population also bred on a short stretch of the Patagonian Atlantic coast of Argentina, but this appears to be ecologically extinct (Bertellotti et al. 2003). From historical times the Guanay Cormorant has been the dominant avian species in the Peruvian Coastal Current in terms of numbers and consumption of marine resources. The population in Peru was estimated as <4 million birds during the period 1909-1920; 21 million were estimated in 1954 and 3.7 million were estimated on the north-central Peruvian coast in 1996 (Zavalaga and Paredes 1999). Mass dispersal, breeding failures and temporary declines have resulted periodically from El Niño Southern Oscillation (ENSO) events, and both fish-stocks and the populations of seabirds that depend on them are adapted to these fluctuations. Although the species is now protected in Peru, fishing for anchoveta is banned, and the guano industry is adequately regulated, there are concerns that this species has been badly affected by the ENSO event of 1998 (G. Engblom in litt. 2003), and that declines now approach 30% over three generations (33 years in this species).