Preference for an invasive fruit trumps fruit abundance in selection by an introduced bird in the Society Islands, French Polynesia

Abstract

Introduced plants with fleshy fruit can alter the dietary decisions of frugivorous birds in their novel ranges by producing fruit of higher quality or by producing fruit in greater abundance. We used fruit choice experiments with wild-caught captive Red-vented Bulbuls (Pycnonotus cafer) on the tropical Pacific island of Moorea, French Polynesia, to determine whether this bird prefers the fruit of a highly invasive tree (Miconia calvescens) over three other fruit (one alien, two native) and to determine whether birds would eat less preferred fruit when it was more abundant than preferred fruit. Birds showed consistent preferences, and chose M. calvescens more than any other species. Birds selected more abundant fruit first when a single species was presented. However, when both fruit species and abundance were modified simultaneously, patterns of preference for particular species remained intact while the response to abundance disappeared. Results imply that dietary preferences are more important than small-scale variations in abundance for fruit selection. The strong preference for M. calvescens suggests that Bulbuls will select the fruit even in habitats where it is rare.