Wednesday, May 16, 2012

Notes on the vocalizations of Greater Pewee

Much more study is needed on all aspects of this topic, especially differences in vocalizations between subspecies.

J.F. Chace & R.C. Tweit, 1999, Birds of North America Online

The Greater Pewee (Contopus pertinax) is found from the southwestern United States (Arizona and New Mexico) south through Mexico to Guatemala, El Salvador, Honduras and northwestern Nicaragua. Northern populations are short-distance migrants, while southern populations remain in their pine-oak habitat year-round. During winter in Central America, Greater Pewees often join mixed insectivorous flocks (warblers, flycatchers, vireos etc) and are usually a prominent member of such flocks, as they perch conspicuously while giving their characteristic "pip-pip-pip" call. 

At the end of the winter, such flocks dissolve as wintering warblers migrate northward and resident species, like the Greater Pewee, stake out territories. I first heard the dawn song of the Greater Pewee on April 3, from outside our bedroom window. Since then, it's been singing that song practically every morning for 15 or 20 minutes or so, a little before sunrise. It's often the first thing I hear waking up in the morning.

That song sounds noticeably different from the many "José Maria" type songs posted on Xeno Canto, which are all from either the United States or Mexico. (The only two recordings on XC from Central America besides mine are of "pip-pip-pip" calls from Guatemala.) The BNA account calls this song, rather accurately I think, "Fred-rick fear", belonging to the Central American subspecies minor. In Cornell's Macaulay Library I found a recording from El Salvador, made by Walter Thurber on 27 November 1975 of that song. 

Today I recorded another Greater Pewee vocalization ("weeew") not previously represented in Xeno Canto. This call is vaguely reminiscent of Dusky-capped Flycatcher — like Greater Pewee a common bird in Central American pine-oak forest. I wasn't able to find this in the Macaulay Library, but it turns out that the Borror Laboratory of Bioacoustics has a recording from Arizona that is similar. I have not seen any descriptions of this call in the literature, and I remember being puzzled by it when I first heard it back in the winter of 2006/2007, during my first field season in Central America.

It actually sounds a lot like the second half of the Central American "Fred-rick fear" song (i.e. "fear"). This occurred to me only after looking at sonograms of these vocalizations.

The bird giving this "weeew" (or "fear") call was perched high on a snag of a nearly dead pine tree. It gave this call for several minutes. When I approached it for a recording, it flew off but quickly returned to the same perch, producing the same vocalization over and over. After a while, however, it started giving a different call. I tried to grab this much softer call ("prrit-prrit-prrit-prrit"), but wind made it difficult to obtain more than a few seconds. Andrew Spencer obtained a much better recording of this call type from Arizona on 20 May 2009, noting in his description that "the first vocalization in this cut is undescribed in BNA; I am not sure what its context is". Perhaps we should have searched for a nest in the tree from which these vocalizations were given.

Cited literature
Chace, Jameson F. and Robert C. Tweit. 1999. Greater Pewee (Contopus pertinax), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:

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