Microsatellite Analysis Reveals Genetic Monogamy Among Female Boreal Owls

Extra-pair fertilizations (EPFs) occur in over 86% of passerine species that have been studied but only in about 45% of nonpasserine birds (Westneat and Sherman 1997). EPFs have been documented at low rates in some diurnal raptors (Korpimᾱki et al. 1996, Negro et al. 1996) and owls might be expected to show similarly low rates due to their similar ecologies (e.g., reversed sexual dimorphism, necessity for male parental care, relatively low densities). Previous studies of owls, however, have shown strict genetic monogamy (Lawless et al. 1997, Marks et al. 1999, Mῡller et al. 2001, Arsenault et al. 2002), in which the male that provisions the nest is the genetic sire of all offspring.