Species: The biology of Mountain Chickadee (alpha code MOCH) is similar to that of the Black-capped Chickadee (P. atricapilla or BCCH), and they may hybridize where their ranges overlap (although BCCH tends to stay with hardwoods vs. evergreens). Also similar genetically to the Mexican Chickadee (P. sclateri). There are four to seven subspecies (hard to distinguish between them).
Identification: Adults have a black stripe from their eye to the back of their head, with a white "eyebrow" or supercilliary stripe above it (which can wear away and even disappear in summer months), topped with a black cap. Below the white eyestripe the cheek is white. The chin and throat are black. The back, wings and tail are gray (with some olive/tan tones - color may vary by location). The belly is grayish white. Sexes look the same, except males are slightly bigger with longer wings. Juveniles look like adults, except they are smaller. Distinguishing from Black-capped Chickadee - white eyebrow, slightly longer bill, wings with a shorter tail, plain grayish wings (Black-capped have more white edges on their secondary feathers.)
Song: A slightly harsher, slower more buzzy song than the Black-capped Chickadee. Clear, high whistles with 3-6 syllables, varies by location.
Distribution: Common in evergreen forests in mountains from southern Arizona, Baja California north to British Columbia and Yukon Territory (BNA). West and central Montana and west Texas? (Western Bird's Nests). Often resident, but some migrate in fall after breeding; when conifer seeds are scarce, they may spread out to lowlands in what is called "eruptive migration." See BBS Map.
Preferred Nesting Habitat: Montane coniferous forest, especially with pine, spruce-fur and piñon-juniper with sparse tree canopy and open understory.
Diet: Depending on time of year, 53-73% insects (moths and caterpillar adults, eggs, pupae, sawfly, beetles, aphids, leafhoppers, scale insects) and spiders; and conifer seeds. Caches conifer seeds. Common bird feeder visitor (large seeds, suet)
Nesting Behavior: Monogamous. Territorial during nesting season (at least until eggs hatch). Breeding territory about 6.5 hectares. May give Snake Display when object (like a mirror) is inserted into cavity or when a human approaches. Will not return to a failed nest site, but may re-use successful sites in subsequent years. Female roosts in nest cavity from building nest until nestlings are fully feathered. Sometimes sits on rim of nest. Tremble-thrusting occurs.
Nestboxes: Seldom picks cavities with entrances much larger than body diameter. Sometimes roosts in boxes or old nests. Will nest in rotten stubs but prefers hard-walled cavities. Will use wooden, sawdust and concrete nestboxes.
Nestbox Location: No preference for compass direction of entrance. May prefer boxes over natural cavities. For natural cavities, use ones that are high (e.g., 4.82-15.6 meters [BNA], 18 inches-80 feet [Western Bird's Nests) in large trees. Typically 6-15 feet high (Western Bird's nests); 4-10 feet high (Mountain Bluebird), may prefer high boxes.
Recommended distance between nestboxes: ? Nearby Pygmy Nuthatches may harass neighboring MOCHs.
Monitoring: Unincubated eggs usually covered with a fur plug. which makes counting difficult (do not touch eggs as they may be very fragile.) When monitor approaches box, adult outside may give loud Chick-a-Dee-Dee-Dee call, and do snake display on nest. Weekly monitoring after hatching is usually okay. Young may prematurely fledge on or after day 13 if disturbed.
Other tips relative to Black-capped Chickadees which MAY apply to MOCHs: Tap the box or whistle to let a brooding female know you are approaching the box - otherwise she may fly into your face. Chickadee egg shells have a very thin shell, and can break even from a light touch. Chickadees are prone to early fledging if disturbed.It's probably a good idea not to open the box after they are 10-11 days old. After that date, you could look in with an automotive mechanic's mirror if you are concerned.
Nesting Timetable (typical):
Excavation or nest site selection: Pairs form in September or by early spring. Uses pre-existing cavities. Male shows female sites, female selects site. Chickadees are very maneuverable and can do a U-turn in a small space like a nest box. I've seen them rapidly and deftly fly underneath a Wren Guard.
Nest construction: Begins less than 1 week before laying. Circular base of rotten wood chips or lichen, moss, grass, with loose fur (from mammal scat, owl pellets, clumps of fur stuck on fences, pulled directly from animals, etc.) or plant down on top, then a distinct cup molded in fur and plugged with looser fur. (Note: Tina Mitchell of CO finds MOCH's nesting in her area do NOT use a fur plug, although Juniper Titmice do.) Nest additions continue after laying.
Egg laying: April - June, depending on location. Older females lay earlier. In cold temperatures, early clutches may fail to hatch, maybe because female is away from the nest while looking for food. Nestboxes and extra food may result in earlier laying. Typically lay one egg per day, 7-9 eggs (sets of 10-12 have been seen - result of egg dumping? Birder's Handbook says 5-9). Unincubated eggs usually covered with a fur plug. Only female incubates. Eggs are ovate to rounded-ovate, some unmarked pure, dead white to entirely marked with tiny reddish-brown dots which may be concentrated on the large end, smooth shells, little or no gloss.
Incubation: 12-15 days (avg. 14.6 days), depending on weather. Only the female incubates and broods. early clutches may not make it during cold temperatures.
Hatching: Hatchlings peep faintly the day they hatch. Adults remove eggshells after hatching. The nestlings have tufts of natal down on their head and spine, and their eyes are closed. Rictal flanges are yellow.
Development: Nestlings are fed whole arthropods. By day 2 they can lift their heads, they beg in response to sound by day 3 and open their eyes on day 6. Fully feathered at 10-11 days. Males may bring in nest material while nestlings are present. Parents remove fecal sacs. Older nestlings may wing quiver while begging. Male sometimes broods young while female is out. May faintly call (fee-bee, chick-a-dee) when approaching the nest with food. Each nestling is fed 15-45 times a day, depending on age. Excrement may accumulate in the nest 1-2 days before fledging.
Fledging: 18-21 days (longer than Black-capped Chickadee). They can fly about 25 m at first, after 2-3 days they can fly more strongly.
Dispersal: Fledglings stay with parents and beg for 2-3 weeks. Dispersal 30 days after fledging, all disperse in first summer. Juveniles may hang together until they join up with a larger group (e.g., with 3 pairs of adults and juveniles.) Groups tend to stay together from year to year. May flock together with Chestnut-backed or Black-capped Chickadees and Juniper Titmice outside of breeding season.
Number of broods: Second brood may occur after cold, wet weather during an early first brood. Picks a different cavity for a second clutch or re-nesting attempt, but often reuses site in subsequent years.
Longevity: The record is a 10 year old wild male (Dixon 1975, BNA)
Mccallum, D. Archibald, Ralph Grundel and Donald L. Dahlsten. 1999. Mountain Chickadee (Poecile gambeli), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/453
Nest and Egg ID (with links to species biology and photos of nests, eggs and young) for other small cavity nesters
The chickadee is a voluble little bird; when two or more are together they are full of conversation, exchanging bright, cheery remarks back and forth.
- Windsor Marrett Tylor, Life Histories of Familiar North American Birds, Black-capped Chickadee, 1947
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