Distribution and abundance of the Yuma clapper rail (Rallus longirostris yumanensis) in the Colorado River delta, Mexico

We estimated the abundance of Yuma clapper rails in the Cienega de Santa Clara and determined the distribution of the subspecies in the Colorado River delta region in Mexico, The maximum estimate of abundance was 6629 individuals (95% C.I. 4859-8399), assuming a response rate by rails to taped calls of 60%. Rails were widely distributed in the delta, occupying almost all marshlands dominated by cattail. As this is an endangered subspecies shared by Mexico and the U.S., the conservation of the delta ecosystem should be the interest of both countries, especially when water management decisions upstream in the U.S. have an impact over natural areas downstream in Mexico. (C) 2001 Academic Press.