We experimentally parasitized Northern Mockingbird (Mimus polyglottos) nests to determine whether that species is more likely to eject immaculate eggs of the Bronzed Cowbird (Molothrus aeneus) or the spotted eggs of the Brown-headed Cowbird (M. ater); the latter species lays eggs that more closely resemble mockingbird eggs. Mockingbirds ejected 69% of model Bronzed Cowbird eggs, indicating that contrary to previous evidence Northern Mockingbirds eject Bronzed Cowbirds eggs at a high frequency. Mockingbirds also ejected 60% of model and real Brown-headed Cowbird eggs. Bronzed Cowbird eggs were ejected faster than Brown-headed Cowbird eggs (1.3 and 2.1 days, respectively). Ejection by mockingbirds may account for the lack of observed parasitism at our study sites in southern Texas, but it is more likely that cowbirds did not parasitize mockingbirds.
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.