The population is estimated to number c.591,000 breeding pairs, equivalent to c.1.18 million mature individuals (likely to equate to at least 1.7 million total individuals) (Naughton et al. 2007). This estimate is based on standardized surveys at Midway Atoll, Laysan Island and French Frigate Shoals in 2006 (551,940 pairs; 25,780 95% C.I.; Flint 2007). These three colonies support 90% of the global breeding population. Estimates for the other colonies are the most recent available (1982-2006). There are c.23 pairs breeding on the Bonin Islands in Japan, and c.400 pairs on islands offshore from Mexico (primarily Isla Guadalupe, 337 pairs estimated in 2005) (Naughton et al. 2007). Data from Hawaiian colonies suggests that a proportion of the breeding population do not breed each year, and as such the population may be greater than estimated here (L. Young in litt. 2009).
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