We studied the intraspecific territorial defense behavior of wintering Willow Flycatchers (Empidonax traillii) in Costa Rica using a randomized playback experiment that exposed male and female birds to recordings of Willow Flycatcher songs and calls, Lesser Ground Cuckoo (Morococcyx erythropygius) vocalizations, and random noise. Flycatchers of both sexes responded most strongly to simulated conspecific territory intrusion, and the agonistic behaviors that we observed were similar to those seen during natural intraspecific encounters in winter. Both males and females engaged in song and aggressive behaviors in defense of territories, and there was no significant difference between the sexes in scored agonistic responses. The similarity between the sexes in intraspecific territorial defense behaviors and aggressiveness may account for both sexes of flycatchers using the same habitats at our study sites in Costa Rica, and wintering females defending territories against males. The Willow Flycatcher, a sexually monomorphic species, differs in this way from a number of sexually dimorphic passerines, in which behaviorally dominant males occur in more optimal winter habitats.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 109 • No. 2