Vocal copying by American Robin

American Robin in run-on song bout that began with an imitation of Eastern Kingbird. Normal singing posture is more relaxed and upright. Pencil sketch copyright David Sibley.

On 5 April 2011 in Concord Massachusetts I was walking the edge of a field where I often go birding, and heard very distinctly the sputtering call of an Eastern Kingbird. It was about four weeks early for that species, and I assumed it was a European Starling mimicking from the trees above me, but when I heard the sound repeated four or five times in succession, with no other Starling-like sounds interspersed, I took notice.

Looking up into the bare trees I found several American Robins, one of which was in an alert horizontal pose, and was clearly vocalizing but in an odd and unfamiliar pattern.

The familiar song of American Robin is a series of relatively low, warbled phrases delivered at a steady pace. Often transcribed as cheerily, cheer-up, cheerio, chee-ridip. Typically 4-6 phrases are sung in rapid succession, then a brief pause about as long as one song phrase, then another set of 4-6 phrases, and so on.

An individual phrase (like cheerio) is usually given once or twice in each set, used in several sets, then dropped for minutes. So as a Robin sings it works through its repertoire of phrases, only occasionally repeating a phrase twice in succession, but coming back to the same phrase repeatedly over the course of 30 seconds or so of singing.

If we assign a letter to identify each unique phrase a Robin sings, the pattern would read something like this: ABCDB ACCD BDEEF FCGEHG and so on.

Occasionally a much higher and more complex phrase is dropped into the sequence, sometimes transcribed as hissely, this has been called “whisper song” (although it’s not really analogous to whisper songs of other species) and a high breathy phrase like this often comes at the end of a Robin’s bout of singing. Nathan Pieplow has posted a summary with recordings of these variations here.

What I was hearing from this robin was a continuous series of hissely-type phrases, much higher than the normal song, and the singing bout continued for over five minutes with only occasional brief pauses! There was also far more repetition of phrases than in typical song, in a pattern more like AABACBABABABCCDCDCEFEEFGHG… Finally, the bird was in an odd posture (shown in the sketch at right) unlike the typical Robin singing pose, perhaps threatening, but it didn’t obviously interact in any way with the few other robins nearby. This might be a “whisper” song. I’m a little more comfortable calling it a “run-on” song, but open to correction if anyone knows the proper terminology.

After the initial imitation of Eastern Kingbird, the only other phrase that sounded like a copy of another species was a snippet of Wood Thrush song, although there were some phrases that sounded like they might have been “inspired by” Eastern Phoebe song, House Finch flight call, and perhaps others. There was no repeat of the near-perfect copy of Eastern Kingbird later in the singing bout.

The fact that American Robin occasionally copies other species is not so surprising. Constantine et al (2006) go as far as to say that “all passerines include mimicry somewhere in their repertoires”. And copies are more common in certain contexts, such as the unformed “practice” songs of immature birds.

I find this particular American Robin intriguing, and I can think of several questions that I’d like to answer.

• Is this kind of song performance a rare occurrence, or is it a regular thing that I’ve just never noticed before?
• What is the behavioral context of the run-on song?
• Do Robins often incorporate copies of other species into this version of their song?

References

Constantine, M. et al. 2006. The Sound Approach to Birding. The Sound Approach, Dorset, UK.

Kroodsma, D. 2008. The Backyard Birdsong Guide: A guide to listening. Chronicle Books.

Pieplow, N. 2011. A Robin’s many songs. Web page, http://earbirding.com/blog/archives/2836

Sallabanks, Rex and Frances C. James. 1999. American Robin (Turdus migratorius), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/462

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