Mockingbirds imitate frogs and toads across North America

Abstract

Vocal mimicry is taxonomically widespread among birds, but little is known about mimicry of non-avian models. Prior studies show preferential imitation of avian models whose sounds are acoustically similar to the non-imitative songs of the vocal mimic. Based on these studies and anecdotes about frog imitations by northern mockingbirds (Mimus polyglottos), we hypothesized which anuran models would be most likely to get imitated by mockingbirds across their geographic range. We tested our hypothesis using >40 h of archived mockingbird recordings. Our results showed that mockingbirds imitated at least 12 anuran species, and calls were disproportionately mimicked when they contained dominant frequencies within the vocal range of the mockingbird (750–7000 Hz). Mockingbirds also frequently modified model anuran sounds by leaving out formants and/or truncating call duration. Our results represent the most comprehensive survey for any mimicking species of the imitation of anurans.