A project of

Black-capped Chickadee

The State of Black-capped Chickadees

Regionally: Increasing

A plot of Black-capped Chickadee study area abundance. The x axis show years between 2010 and 2021. The y axis shows local population size. Local population size fluctuates between roughly 100 and 240 individuals and there is an slight upward trend overall.

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.
RegionMean 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>0.9956.06(13.20, 109.56)
New York
(state)
5.71(1.05, 11.34)0.010.9990.84(12.16, 225.87)
New York
(Catskills)
4.17(-2.69, 13.43)0.150.8574.46(-25.93, 300.00)
New York
(Adirondacks)
6.44(1.22, 13.10)<0.01>0.99108.39(14.29, 287.50)
Vermont 2.55(-2.36, 7.90)0.140.8636.62(-23.08, 130.77)
New Hampshire 3.45(-0.20, 7.11)0.030.9747.84(-2.14, 112.90)
Maine 4.30(0.68, 7.87)0.010.9961.58(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.

 

State of the Mountain Birds