Nocturnal hunting by Peregrine Falcons at the Empire State Building, New York City

We report on nocturnal hunting by Peregrine Falcons (Falco peregrinus) at the Empire State Building in Manhattan, New York City. From 4 August through 13 November 2004, we saw Peregrine Falcons on 41 of 77 nights of observation. During this period, they hunted migrating birds on 25 evenings, with the first hunting attempt Occurring an average of 119 min after sunset. Peregrine Falcons made 111 hunting attempts and captured 37 birds (33% success). Hunting Success was highest in September, but was most often observed in October. Peregrines limited migratory birds at night more frequently in autumn than in spring. Peregrines were significantly more likely to be present on autumn nights when > 50 migrants were passing by the Empire State Building. Although the lights associated with skyscrapers are believed to disorient migrating birds and result in many bird-to-skyscraper collisions each year, Peregrine Falcons are able to take advantage of the situation. Skyscrapers provide hunting perches at altitudes often flown by nocturnal migrants, and disorientation caused by the lights sometimes results in birds circling skyscrapers and possibly becoming more vulnerable to predation by falcons.