Population estimates of Nearctic shorebirds

Estimates are presented for the population sizes of 53 species of Nearctic shorebirds occurring regularly in North America, plus four species that bre ed occasionally. Shorebird population sizes were derived from data obtained by a variety of methods from breeding, migration and wintering areas, and formal assessments of accuracy of counts or estimates are rarely available. Accurate estimates exist only for a few species that have been the subject of detailed investigation, and the likely accuracy of most estimates is co nsidered poor or low. Population estimates range from a few tens to several millions. Overall, population estimates most commonly fell in the range of hundreds of thousands, particularly the low hundreds of thousands; estimat ed population sizes for large shorebird species currently all fall below 50 0,000. Population size was inversely related to size (mass) of the species, with a statistically significant negative regression between log (populati on size) and log (mass). Two outlying groups were evident on the regression graph: one, with populations lower than predicted, included species consid ered either to be "at risk" or particularly hard to count, and a second, wi th populations higher than predicted, included two species that are hunted. Population estimates are an integral part of conservation plans being deve loped for shorebirds in the United States and Canada, and may be used to id entify areas of key international and regional importance.