The State of Black-capped Chickadees
Regionally: Increasing
The mean (thick, dark red line) annual estimate of the Black-capped Chickadee abundance within the immediate areas surrounding ~750 Mountain Birdwatch sampling stations. The lighter vertical bars represent the 95% Bayesian credible interval (a measure of the uncertainty around the abundance estimates).
Most of us probably don’t think of Black-capped Chickadees as montane species, but this species can be found as high up as the top of Mt. Mansfield in Vermont. Mountain Birdwatch data suggest that Black-capped Chickadee numbers have increased at an annual rate of 4.02% (95% Bayesian credible interval = 1.13% to 6.96%) in the spruce-fir mountain zone of the northeastern United States since 2010. Black-capped Chickadees were not counted during the first iteration of Mountain Birdwatch (from 2000-2009), so whether recent increases reflect a long-term trend is unclear. However, in 2010 Black-capped Chickadees were absent from the six Mountain Birdwatch routes in the Catskills. Our models estimate that there are now between 10 and 18 Black-capped Chickadees along these six routes in 2021, despite no obvious changes to the forest composition. Similar, in Maine, our models estimate that the population size Black-Capped Chickadees along these six Mountain Birdwatch routes has increased from ~8 to ~36 over the last decade. While these numbers are impressive, there are two points to keep in mind. 1) Black-capped Chickadees are still very rare in the spruce-fir zone along Mountain Birdwatch routes, so their trends are disproportionately affected by the addition or subtraction of a few individuals. We would probably want several thousand (as opposed to ~750) sampling stations to adequately describe the population dynamics of this species in our spruce-fir montane forests. 2) Black-capped Chickadees certainly breed in the spruce-fir zone at low densities, and they nest atop Mt. Mansfield, but the figure above suggests that Black-capped Chickadees may be erratic into this forest biome in some years. Boreal Chickadees, for example, are also known to be erratic from year-to-year: they may be locally common one year, and entirely absent the next–perhaps related to local food availability and abundance.
Mean annual population trends and population change (with 95% Bayesian credible intervals [CRI]) for Black-capped Chickadee from 2010 through 2021. A blue dot
indicates weak evidence for a positive trend, while a purple dot 
indicates strong evidence for a positive trend.
| Region | Mean annual trend (%) | Trend 95% CRI | Probability of decrease | Probability of increase | Population change (%) 2010-2021 | Population change (95% CRI) |
|---|---|---|---|---|---|---|
| All regions |  4.02 | (1.13, 6.96) | <0.01 | >0.99 | 56.06 | (13.20, 109.56) |
| New York (state) | 5.71 | (1.05, 11.34) | 0.01 | 0.99 | 90.84 | (12.16, 225.87) |
| New York (Catskills) | 4.17 | (-2.69, 13.43) | 0.15 | 0.85 | 74.46 | (-25.93, 300.00) |
| New York (Adirondacks) | 6.44 | (1.22, 13.10) | <0.01 | >0.99 | 108.39 | (14.29, 287.50) |
| Vermont | 2.55 | (-2.36, 7.90) | 0.14 | 0.86 | 36.62 | (-23.08, 130.77) |
| New Hampshire | 3.45 | (-0.20, 7.11) | 0.03 | 0.97 | 47.84 | (-2.14, 112.90) |
| Maine | 4.30 | (0.68, 7.87) | 0.01 | 0.99 | 61.58 | (7.69, 130.00) |
Globally: Increasing
Data from the North American Breeding Bird Survey indicate the Black-capped Chickadee numbers are overall increasing across the United States and Canada (~0.5% per year). These increases, however, are largely confined to the upper Midwest and the eastern half of the species’ range; Black-capped Chickadees trends are negative in the lower Midwest and much of the western US and Canada.
