Infanticide by an Eastern Phoebe

Abstract

We videotaped an Eastern Phoebe (Sayornis phoebe) nest in central Kentucky on 22 June 2008 and documented a case of infanticide. An adult male phoebe, likely the resident male, was captured at the nest site on 21 June 2008. The resident female fed nestlings (3, ∼8 days of age) 69 times during a 4.1-hr taping session (0815–1221 hrs EDT) the next day, but the resident male was not observed at the nest. Beginning at 0923 hrs, an intruding phoebe (likely a male) occasionally visited the nest, sometimes pecking at, but not feeding, the nestlings; this phoebe initiated a vigorous attack at 1151 hrs, pecking and pulling the head of one of the nestlings for 25 min before pulling it out of the nest. The intruding phoebe returned after a short absence, just before the end of the videotape, and began attacking another nestling. The nest was empty when checked the next day. Suitable territories and nest sites may be limiting factors for Eastern Phoebes, and infanticide by non-breeding males may enhance their reproductive success if the resident female or a new female subsequently pairs with the male and initiates a new nest.