The effect of different schedules of reinforcement on the structure of the black-capped chickadees’ chick-a-dee call.

Abstract

It is known that adult songbirds can modify the output and structure of their vocalizations in different behavioral contexts. However, whether changes in the abiotic environment (i.e., food availability) also affect vocal structure is less understood. Here we test whether the chick‐a‐dee calls of the black‐capped chickadee differ between birds on two different schedules of reinforcement (continuous and partial) and in two different behavioral contexts (singing alone and mildly alarmed by human intrusion). Our results reveal differences in the composition and pitch of chick‐a‐dee calls from birds in different behavioral contexts and on different schedules of reinforcement. However, calls from birds on the different schedules of reinforcement become more similar when evoked by human intrusion. We suggest that these results may represent differences in the energy dedicated to call production. If vocal structure varies consistently with changes to the abiotic environment, we may be able to detect environmental changes (i.e., warming and reduction in available forage) through analysis of vocal traits. While we demonstrate differences in call structure based on schedules of reinforcement, results from field studies in multiple regions will divulge whether these vocal changes are consistent and useful for analysis of abiotic conditions.