Mockingbirds imitate frogs and toads across North America

Area of Science:

• Bioacoustics
• Animal behavior
• Ornithology

Background:

• Vocal mimicry is common in birds, but imitation of non-avian species is less understood.
• Previous research suggests birds prefer mimicking acoustically similar avian models.

Purpose of the Study:

• To investigate which anuran (frog) species are most likely to be imitated by northern mockingbirds (Mimus polyglottos).
• To determine the acoustic features that influence the likelihood of anuran call imitation by mockingbirds.

Main Methods:

• Analysis of over 40 hours of archived northern mockingbird recordings.
• Identification and cataloging of imitated anuran vocalizations within the recordings.
• Acoustic analysis of imitated calls, focusing on dominant frequencies and modifications.

Main Results:

• Mockingbirds imitated at least 12 anuran species.
• Calls with dominant frequencies between 750-7000 Hz were disproportionately mimicked.
• Mockingbirds frequently altered anuran sounds, omitting formants and shortening call duration.

Conclusions:

• Northern mockingbirds exhibit a broad repertoire of anuran mimicry.
• Acoustic properties, specifically dominant frequency, play a significant role in model selection for mimicry.
• Mockingbirds actively modify imitated sounds, suggesting complex vocal learning and adaptation.