Extra-Pair Mating Tactics and Vocal Behavior of Female Acadian Flycatchers

Abstract

Abstract. In many passerines, rates of extra-pair paternity are high, but relatively few studies have examined the behaviors females use to obtain extra-pair copulations. We studied extra-pair behavior in females of the Acadian Flycatcher (Empidonax virescens), a species in which 58% of females produce extra-pair young and males often sire offspring on distant territories. We used radiotelemetry to document the extent and frequency of females' forays away from their territories and used behavioral observations and playback experiments to test if females' vocalizations advertise their fertility. No radio-tagged females left their territories (n = 12 females, 105 hr of tracking) even during the hour before dawn. Paternity analyses revealed that at least six of these females produced extrapair young. Focal observations revealed that fertile females spent significantly more time calling “chiff,” gave more calls per hour, and called in longer bouts than did incubating females. Extent of females' chiffing durin...