Minimum population of American Oystercatchers Haematopus palliatus frazari wintering in northwestern Mexico

Although there are few American Oystercatchers of the subspecies Haematopus palliatus frazari, there is no accurate estimate of the population size. We visited 14 sites in northwestern Mexico during December 2013 and recorded 2,366 H. p. frazari. The main congregations were concentrated in two regions: between the center of Sinaloa and southern Sonora (55.5%) and western middle of the Baja California Peninsula (27.3%). As our survey area included 86% of the wetlands in the region, we believe that it included a large proportion of the total wintering population and that it is unlikely that the total number of frazari oystercatchers in northwestern Mexico is much higher than our count. We identified two important areas that had not been documented previously (Bahía Tóbari and Agiabampo, located between the north of Sinaloa and the south of Sonora), which together comprised 31% of the total records.