Sunday, February 13, 2011

Coincidence or mimicry?

male Green-breasted Mountain-gem, Honduras, February 2011
The Green-breasted Mountain-gem, a hummingbird from central Honduras and western Nicaragua, sings a soft song that usually starts with a scratchy warble, or sometimes with variations of its buzzy call, and occasionally is embellished with a fast, lower trill at the end. Its sister species, the Green-throated Mountain-gem, sings a similar song.

That last part, the trill, is not always sung. I've recorded individuals that sang a few introductory phrases, and then broke off. Male mountain-gems usually sing this song from a perch, although I have heard (and recorded) the whole song, including the trill, being sung in flight, while the singer was pursuing another individual (male or female, who knows).

Ericsson 1950s bakelite telephone*
To my ears, the trill sounds a little bit like an old telephone: not the sound the telephone makes with an incoming call ("old telephone ring tone"), but rather the sound you'd hear from the receiver telling you the phone is ringing at the other end.

Last week, I was very surprised to hear a Slate-colored Solitaire finish its beautiful song with a similar phrase! This was in Monte Uyuca, Honduras, where Roselvy and I carried out SalvaNATURA's monthly bird monitoring pulse.

Slate-colored Solitaire, Honduras, January 2011
I researched this a little, and found that none of the eight Slate-colored Solitaires available through xeno-canto sing this phrase. Cornell's Macaulay Library has many more Slate-colored Solitaire songs, including extensive recordings from El Salvador made by Walter Thurber in the 1970's, but I didn't hear it there either. I did hear a wonderful variety in phrasing of this haunting, ethereal song, so characteristic of Central American cloud forests.

First listen to two Slate-colored Solitaire songs, both from the same individual:

Now listen to a recording of two songs of a Green-breasted Mountain-gem, made within 15 minutes and 20 meters of where that solitaire was singing:

To my ears, the last phrase in the Slate-colored Solitaire's song from Uyuca sounds a lot like the last phrase in each of the two songs of the Green-breasted Mountain-gem. Is this mere coincidence, or is the solitaire, a wonderfully accomplished singer, actually paying tribute in song to the more modest vocal skills of its neighbor, the mountain-gem?

*image licensed under Creative Commons Attribution Share-Alike 3.0 Unported

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