Effects of Gargle Vocalizations on Behavior of Black-Capped Chickadees

Abstract

In agonistic situations, Black-capped Chickadees (Parus atricapillus) utter a short, structurally complex call termed a gargle. Previous work has shown that in contests between two birds at food sources the gargler always wins. We investigated the establishment of the relationship between gargling and dominance by pairing males that were strangers. Our results indicate that dominance is established by fighting and that the dominants are larger than subordinates. In the earliest phase of the first encounter, a dominant bird would utter gargles concurrent with aggressive actions whereas a subordinate's gargling was suppressed and remained so indefinitely. We also investigated the separate effects of the gargle calls, the partner bird, or both in an experimental presentation. Results indicate that the subordinate was not kept away from a food source by the gargle calls of its dominant partner, but it was deterred by the presence of the partner. Dominants, on the other hand, were somewhat deterred by the gargle of their subordinate partner but not by the presence of the partner.