Several Black-capped Chickadees with dilute plumage (lacking some melanin pigment) have been recorded. These birds have paler brownish caps and can be confused with Boreal or Gray-headed Chickadees. One such bird was in Seneca Co., NY, in July 2004 (Photos and discussion here http://www.birds.cornell.edu/crows/brown-headed%20chickadee.htm). A similar but somewhat paler bird was seen in Rednersville, Ontario, January 2004; and another was in Kingston, Rhode Island around Dec-Jan, 1995-96.
These pale Black-cappeds were distinguished from Boreal Chickadee by their completely white neck sides (rear cheeks), obvious white edges of secondaries and tail, and weak buff wash on flanks. Voice would also be a good ID clue, as the NY individual reportedly gave typical Black-capped calls as expected.
A similar dilute plumage Black-capped Chickadee in or near the range of Gray-headed could be confused with that species, as was the case in Edmonton, Alberta in 1979. ((see Thormin and Tull. 1980. The Ex-Gray-headed Chickadee. Birding 12(2): 62-64)) Features leading to that bird’s identification as dilute-plumage Black-capped rather than Gray-headed include:
- Obvious contrast between dark cap and paler back (vs. Gray-headed with cap and back very similar in color)
A dilute-plumage Black-capped should have melanin reduced equally in all parts of the plumage, preserving the contrast between cap and back.
- Three outer tail feathers broadly edged white (vs. Gray-headed with pale edging only on outer two feathers)
- Flanks paler than Gray-headed, a wash of pale buff (vs. darker cinnamon on Gray-headed)
- Crown more brownish (vs. more or less neutral gray on Gray-headed)
It’s possible that some Black-capped Chickadees with dilute plumage might show a grayish crown, but all of the known records listed here involve Black-capped Chickadees with distinctly brownish caps.
- Overall paler than Gray-headed