The State of Black-capped Chickadees
Regionally: Increasing
The mean (thick, dark line) annual estimate of Black-capped Chickadee abundance—calculated as the annual sum of estimated Black-capped Chickadee within the local area (a 4-hectare circle) surrounding all 791 Mountain Birdwatch sampling stations. The thinner, lighter lines represent less probable estimates of the annual abundance.
Most of us probably don’t think of Black-capped Chickadees as a montane species, but this species readily adapts to human-modified landscapes–including mountain summits if there’s human presence. For example, this species can be found in high densities within the spruce-fir forest around the upper parking lot near the top of Mt. Mansfield in Vermont. Mountain Birdwatch data suggest that Black-capped Chickadee numbers have increased at an annual rate of 2.22% (80% Bayesian credible interval = -1.17% to 5.60%) 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 initial Mountain Birdwatch routes in the Catskills. Our models estimate that there are now likely >20 Black-capped Chickadees around the sampling stations along these six routes in 2023, despite no obvious changes to the forest composition. While this growth is 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 each year. 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 80% Bayesian credible intervals [CRI]) for Black-capped Chickadee from 2010 through 2023. An orange dot
indicates weak evidence for a negative trend. A blue dot 
indicates weak evidence for a positive trend, while a purple dot 
indicates strong evidence for a positive trend. Strong evidence is suggested for a trend when the 80% CRI does not contain zero.
| Region | Mean annual trend (%) | Trend (80% CRI) | Probability of decrease | Probability of increase | Population change (%) 2010-2023 | Population change (80% CRI) |
|---|---|---|---|---|---|---|
| All regions |  2.22 | (-1.17, 5.60) | 0.20 | 0.80 | 33.07 | (-14.16, 102.96) |
| New York (Catskills) |  6.56 | (2.1, 10.91) | 0.03 | 0.97 | 128.31 | (31.01, 284.30) |
| New York (Adirondacks) | 4.51 | (0.43, 8.58) | 0.07 | 0.92 | 77.43 | (5.76, 191.65) |
| Vermont | 2.23 | (-1.56, 6.02) | 0.23 | 0.77 | 33.14 | (-18.48, 113.71) |
| New Hampshire | -1.37 | (-5.08, 2.41) | 0.69 | 0.31 | -16.45 | (-49.21, 36.35) |
| Maine | 3.99 | (0.13, 7.79) | 0.09 | 0.91 | 66.21 | (1.67, 165.06) |
Globally: Uncertain
Data from the North American Breeding Bird Survey suggest that Black-capped Chickadee numbers are overall increasing across the United States and Canada (~0.6% per year). These increases, however, are largely confined to the upper Midwest and the eastern half of the species’ range. In contrast, eBird trends suggest that Black-capped Chickadee numbers have declined by as much as 20% over the last decade in the eastern U.S.
