Productivity, mortality, and management of urban peregrine falcons in northeastern North America

Abstract

The peregrine falcon (Falco peregrinus) population in eastern North America has grown significantly since the early 1980s, especially in urban areas, but few studies have assessed the factors that influence productivity. We reviewed all documented nesting attempts from southern Ontario, Quebec, Massachusetts, New Jersey, and Pennsylvania from 1980 through 2006 to evaluate these factors. Of 801 nesting attempts, 663 were successful, producing a total of 1,613 young. Mean productivity ranged from 1.7 young fledged per nesting attempt in New Jersey to 2.9 in Quebec. Peregrines nesting in quarries or on buildings had higher productivity than those using marsh towers or bridges, but productivity did not differ overall between urban and rural sites. Nests with overhead cover had higher productivity than those without, as did nests in trays or boxes compared to sites without any human-provided nesting aids. Peregrines favored nest sites facing east to south, but productivity did not vary significantly with direction. Several adults have contributed disproportionately to the growth of the eastern population, with just 5 females and males accounting for 8% and 9% of all young fledged, respectively. Of 160 documented mortalities, we identified cause of death for 118, with the most common being collisions with buildings (36%), vehicles (9%), aircraft (8%), and power lines (8%). In many urban areas, grounded fledglings are rescued and returned to higher perches. Of 85 individuals from southern Ontario that were rescued, at least 8 have subsequently bred, producing 65 known offspring. Although peregrines have been thriving in eastern cities, continued management effort may be required for them to maintain their level of success, with key measures including provision of appropriately located nest boxes and rescue of grounded fledglings. © 2014 The Wildlife Society.