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Guanay Cormorant Phalacrocorax bougainvillii

  • Order: Suliformes
  • Family: Phalacrocoracidae
  • Monotypic
  • Authors: Mark A. Baran and Michael G. Harvey

Demography and Populations

Guanay Cormorant populations fluctuate greatly with climatic changes, especially powerful El Niño events (Jordan 1966). In a year with a strong El Niño, the upwelling along the coast declines or ceases entirely, causing a fish population crash. In response, cormorants will abandon nests and disperse far to the north and south in search of food. Millions usually starve (Duffy 1983b).

Population estimates range from < 4 million from 1909 to 1920, to 21 million in 1954 and 1955, to 3.7 million in the same region in 1996 (Zavalaga and Paredes 1999).

Cormorants are afflicted by a number of ectoparasites, including the lice Eidmanniella pellucida and Piagetiella transitans (Sepulveda 1997). The argasid tick (Ornithodoros amblus) can cause nest desertion in years with large tick populationss (Duffy 1983d).

Recommended Citation

Baran, M. A. and M. G. Harvey (2011). Guanay Cormorant (Phalacrocorax bougainvillii), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.