Organization of agonistic vocalizations in black-chinned hummingbirds

Abstract

We describe vocalizations of Black-chinned Hummingbirds (Archilochus alexandri) recorded during agonistic encounters at feeders. Calls are composed of one to five different note-types that comprise a recombinatorial system exhibiting syntax. A Markov analysis revealed non-random ordering of note-types. The distribution of call-types (unique combinations of notes) illustrates openness; the number of call-types increases as more calls are sampled. Constraints on call length occur that are related to the length of individual note-types; shorter note-types are more common in calls with more notes. No sex differences occurred in the call-types with the exception of the Z note which occurred more often in male calls. The agonistic vocalizations of these hummingbirds demonstrate a level of vocal complexity comparable to songs of many passerines. We compare the vocalizations of the Black-chinned Hummingbird with studies of Anna's Hummingbird (Calypte anna) and point out major differences in repertoire organization. Marked similarities occur between organization of calls in certain chickadees (Parus) and that of the Black-chinned Hummingbird. This finding is surprising in view of their phyletic differences, but may reflect certain underlying constraints on the organization of avian vocalizations.