Black-capped Chickadee Poecile atricapillus
See Black-capped vs. Carolina Chickadee
By far the biggest challenge to identifying Black-capped Chickadee is distinguishing it from Carolina in the narrow zone of overlap. Black-capped is slightly more strongly-colored, slightly larger, larger-headed and longer-tailed, and has a slower call, but these are subtle things and can be difficult to judge. Furthermore, many hybrids exist in the contact zone, making positive identification there nearly impossible.
Similar to Black-capped in general appearance, voice, and habits, but readily distinguished by uniform gray wings, white eyebrow, shorter tail, wheezier call, etc. These two species occur side-by-side across much of the west, but Black-capped usually chooses wetter (often riparian) willow and poplar groves, while Mountain favors drier hillside spruce and pine forests.
Obviously darker overall, with gray wings and neck, and browner on the crown, back and flanks. Very wheezy call is also distinctive. Found almost exclusively in forests dominated by spruce and fir, not in predominately broadleaf forests.
Scarce and found only in aspen groves in extremely remote areas of northern Alaska. Differs from Black-capped in grayish cap and cinnamon flanks. Rare dilute plumage Black-cappeds have grayish cap and can be confused, but Gray-headed has crown and back about the same color, while dilute Black-cappeds still have crown darker than back.
Subspecies in the Sibley Guide
Eastern – P. a. atricapillus group
Rocky Mountain – P. a. septentrionalis group
Pacific – P. a. occidentalis group
Geographic variation is mostly clinal, involving small changes in color. It is unlikely that a vagrant from one population could be confidently identified outside of its normal range (and unlikely that any individual would wander that far). Calls are essentially identical throughout the range. Some regional differences in song have been detected (described below).
Geographic Variation in song
Across almost all of the species’ range, song is a simple two-syllabled fee-beee, with the second syllable lower and often with a slight hesitation that makes it sound two-parted fee-beeyee. Only in parts of the Pacific Northwest and on the islands off Massachusetts are different songs heard from Black-capped Chickadees. Hybrids with Carolina Chickadee in the contact zone sing a variety of different songs.
Kroodsma, et al. found the following differences between birds on Nantucket and Martha’s Vineyard, MA, compared to the adjacent mainland:
- most island songs have two whistles on the same pitch (vs. mainland birds have second whistle lower than first)
- island songs much more variable than mainland songs, with breaks in the first, second, or both main whistles (vs. breaks only in second whistle)
- island males typically have repertoires of two or more different songs (vs. mainland birds sing only one song)
- song dialects occur both between and within the islands (vs. no dialects on mainland)
In the Pacific Northwest songs are even more variable, but this variation is essentially unstudied. ((How variable is the song of Pacific birds? Are there regional patterns? Dialects?)) Black-capped Chickadee songs from Willamette Valley, Oregon can be heard here: http://neighborhood-naturalist.com/neighborhood-naturalist_birdsounds.htm
All are multi-syllabled with 4 to 8 or more whistles, and one common pattern is the first three whistles high-pitched, then about 5 more each slightly lower then the one before. Similar songs have been heard south to the southern limit of the species’ range in Humboldt Co, CA (pers. obs.) and as far north as Anchorage, Alaska. ((The eastward limit of these variable songs is unknown. Birds on the east slope of the Rocky Mountains in Montana sing typical two-note songs. It’s likely that these song variants are found only west of the Cascades, but nobody knows.))
Despite their simple black-gray-and-white pattern, research has shown that male Black-capped Chickadees are brighter white and deeper black than females (some of these differences in the near-UV range), and furthermore that socially high-ranking males are brighter than low-ranking males (Mennill et al 2003; Doucet et al, 2005). ((The report that female Black-cappeds prefer brighter males is strange in light of the report from Pennsylvania (Reudink et al., 2005) that female Carolina and Black-capped Chickadees prefer more Carolina-like males, since those seem less bright to our eyes. Maybe Carolina Chickadees have stronger UV reflection, and the birds are really cueing in on the UV signals more than our visible spectrum?))
X Carolina Chickadee – common and extensively studied in narrow contact zone. More details here.
X Mountain Chickadee – very rare even though these two species occur together over a wide area. They are segregated somewhat by habitat, and hybrids have only been reported in New Mexico and Washington.
Doucet, S. M., Mennill, D. J., Montgomerie, R., Boag, P. T., and Ratcliffe, L. M. 2005. Achromatic plumage variation predicts reproductive success in male black-capped chickadees. Behavioral Ecology 16: 218-222. pdf here: http://web2.uwindsor.ca/courses/biology/dmennill/pubs/2005BE218.pdf
Mennill, D. J., Doucet, S. M., Montgomerie, R., and L. M. Ratcliffe. 2003. Achromatic color variation in black-capped chickadees, Poecile atricapilla: black and white signals of sex and rank. Behavioral Ecology and Sociobiology 53: 350-357. pdf here: http://web2.uwindsor.ca/courses/biology/dmennill/pubs/2003BES350.pdf
Reudink, M. W., S. G. Mech, and R. L. Curry. 2006. Extra-pair paternity and mate choice in hybridizing chickadees. Behavioral Ecology 17:56-62. pdf here: http://www98.homepage.villanova.edu/robert.curry/RLC/research.htm#chick