We report a possible hostile takeover of a female (and a territory) by a male American Dipper (Cinclus mexicanus) near Juneau in southeastern Alaska in 2006. The evidence is circumstantial but strongly suggestive, in light of previous studies.
Infanticide by unrelated conspecific individuals, both male and female, is widespread among mammals (Hrdy 1979) and birds (Chek and Robertson 1991, Møller 2004, Veiga 2004). Usurping males kill existing offspring, quickly making the bereft female ready to mate again (e.g., Hrdy 1979, Freed 1986, 1987). In passerine birds, infanticide by adult males occurs in a variety of species (e.g., swallows, wrens, sunbirds, starlings; Møller 1988, Freed 1986, 1987, Kermott et al. 1990, Goldstein et al. 1986, Robertson and Stutchbury 1988, Smith et al. 1996), often giving the usurper a mate or sometimes both a mate and a nest (Hansell 2000). Infanticide by a usurping male at a given nest may be spread over more than one day (Goldstein et al. 1986, Kermott et al. 1990, Yeager 1990).