posted January 29th, 2011; last edited January 29th, 2011 –– David Sibley

Variation in Brown Creeper songs

This post accompanies: Is the Brown Creeper more than one species?

The songs of Brown Creepers do vary regionally, but the variation is subtle and complex and not very obvious (at least to our ears). Regional differences in song may offer the strongest support for splitting Brown Creeper into multiple species, but remain virtually unstudied.

Hejl et al (2002) report, anecdotally, differences in song between study sites in Idaho, coastal Washington, and California (note that the Washington and California samples would presumably both be part of the new Pacific group). Baptista and Johnson (1982) found differences between songs near San Francisco and a site only 140 km south. These results show that there are regional dialects within the potential new “Pacific” species, and similar dialects probably exist within the Rocky Mountain and Eastern populations as well, which will make it harder to detect differences between those larger populations.

Careful comparison of the recordings linked below (songs of Brown Creeper from Xeno-Canto) reveals differences, but much more study is needed to determine how consistent these differences are across populations. Most importantly, field studies are needed to determine whether the birds recognize any differences.

	Recorded in Massachusetts Note the rapid jumble of notes, descending in pitch
	New Jersey
	Wisconsin Sonograms show differences between this and the two other Eastern recordings above, but the sound is quite similar in all three.
	Colorado A more "relaxed" tempo and wider pitch changes give it a "see-saw" sound unlike other populations, with one strongly trilled phrase. Ends with a note similar to the intro but not as high.
	Sierra Nevada Mountains, California Ending with a high clear note matching the intro; more rapid tempo than Colorado, notes delivered a little more crisply than Eastern.
	Huachuca Mountains, Arizona Intro notes widely spaced and trilled, otherwise similar to Eastern but a little looser; lacking the high end note of California birds and the sing-song pattern of Colorado.
	Huachuca Mountains, Arizona Intro notes widely spaced and trilled, main song phrases very similar to Eastern but a bit looser and "sloppier", with less strongly descending pitch overall. Lacks the clear final note of California and Colorado, less sing-song than Colorado; often adds a few extra phrases at end.
	Chiricahua Mountains, Arizona Recorded in the Chiricahua Mountains, where Phillips et al. report a mixed population including typical albescens and typical montana. This recording could fit that hypothesis, as it differs from the Huachuca recording in having a short intro note and more sing-song pattern, both like Colorado.