Rejection of artificial parasite eggs by gray kingbirds in the Bahamas

Abstract

We added artificial Shiny Cowbird (Molothrus bonariensis) eggs to Gray Kingbird (Tyrannus dominicensis) nests in the Bahamas, where Shiny Cowbirds were first recorded in 1993. Gray Kingbirds ejected 85% of artificial eggs within 48 hr of addition. Based upon the short time of contact between the two species, we suggest that egg ejection by Gray Kingbirds in the Bahamas is retention of ejection behavior from ancestral populations.