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Species · Illinois · BBS 2025 Release · 1966–2024

Black-capped Chickadee Population Trend in Illinois

All statesForest birds

Black-capped Chickadee in Illinois has increased: up 28% on the route-weighted index since 1968.

+28%Since 1968TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
77Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-capped Chickadee Trends in IllinoisNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Black-capped Chickadee in Illinois. See the full index history below.

Black-capped Chickadee Population Forecast in Illinois

If the recent trend holds, Black-capped Chickadee in Illinois is projected to stay roughly flat through 2029, near 1.7 (95% range 0.94–2.5). A 5-year backtest shows a typical error of ±32.8%, with 100% of held-out values landing inside the 95% band.

+5%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
1.7Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.94–2.595% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±32.8%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Black-capped Chickadee in Illinois is projected to stay roughly flat through 2029, near 1.7 (95% range 0.94–2.5). A 5-year backtest shows a typical error of ±32.8%, with 100% of held-out values landing inside the 95% band.19662029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20251.70.912.4
20261.70.912.5
20271.70.922.5
20281.70.932.5
20291.70.942.5

Black-capped Chickadee Survey Routes in Illinois

Routes recording Black-capped Chickadee in Illinois.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Barrington2920121971
Wayne2320241968
Belleview1520241966
Caledonia1020241994
Union920172001
Guilford820211974
Alden720232019
Geneseo620211967
New Lenox620191966
Melrose619991973
Seneca620241994
Cherry Val 2620182004
Camp Point520241993
Le Roy520241996
Lake Galena520212001
Athens520241995
Sheffield420241966
Concord420241967
Jamestown419941994
Shannon420241993
Payson420242000
Grape Creek420192018
Mill Creek320241966
Stillwell320241978
Williamsfld320231978

Black-capped Chickadee Population Trend in Other States

alaskacaliforniacoloradoconnecticutidahoindianaiowakansasmainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseeutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.