Population Estimates for Northern Juvenile Peregrine Falcons With Implications for Harvest Levels in North America

Abstract

Abstract I used a Lincoln–Petersen model to estimate the population size of northern-reared hatch-year (the cohort of individuals known to have hatched during the calendar year in which they were banded) peregrine falcons (Falco peregrinus) based on mark and recapture data from northern North America (including Greenland) from 1970 through 2010. This analysis supported a previous finding that migratory populations in western and eastern North America tend to remain separate, and are best analyzed as two distinct populations. The annualized Lincoln–Petersen estimate for the western population was 16,035 ± 2,040 falcons, and 5,245 ± 500 falcons for the eastern population, or approximately 21,000 hatch-year falcons when summed. Using productivity of 1.4 young/occupied site resulted in an estimate of the northern breeding population of more than 15,000 pairs or 30,000 breeding adults. Assuming that the number of nonbreeding adults was equal to the number of breeding adults, the estimated total annualized adult breeding-aged population was in excess of 60,000 falcons, and the total combined population at the end of a breeding season was in the order of 80,000 falcons by the year 2000. The peregrine falcon is no longer legally threatened in Canada or the United States, and legal harvest of wild-caught migratory peregrine falcons is permitted for the practice of falconry. Using the U.S. Fish and Wildlife Service harvest guideline, and the annualized estimate of hatch-year falcons reported here (after mortality), it appears that the combined annual harvest limit in Canada, the United States, and Mexico could be conservatively set at 840 hatch-year falcons without negative impact to the breeding population.