DistributionRead full entry
Range DescriptionPuffinus opisthomelas breeds on six islands or small islets (including Guadalupe, San Benito and Natividad), off the Pacific coast of Mexico. Recent censuses have found the population to be much larger than previously thought. On Natividad, the population was estimated at 76,000 pairs in 1997 (Keitt 1998), compared with 5,000-10,000 pairs in 1991 (Everett and Anderson 1991). On San Benito, there are at least several thousand pairs (B. Tershy and B. Keitt in litt. 1999), but only 250-500 pairs were estimated in 1991 (Everett and Anderson 1991). On Guadalupe, the population was estimated at 2,500 pairs in 1991 (Everett and Anderson 1991). The current world population is estimated between 55,000 and 95,000 pairs, with the vast majority of the world's population (>95%) occurring on one island (Natividad) (B Keitt in litt. 2003). On Natividad, there was a 15% decrease in habitat and a 13-20% loss in burrows between c.1970 and the mid-1990s, and the estimated population decline was 4% per annum (Keitt 1998). Birds disperse mainly to the north reaching central California, USA, and rarely British Columbia, Canada (Carboneras 1992d).