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Species · Illinois · BBS 2025 Release · 1966–2024

Hairy Woodpecker Population Trend in Illinois

All statesForest birds

Hairy Woodpecker in Illinois has surged: up 136% on the route-weighted index since 1968.

+136%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 →
90Routes 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 Hairy Woodpecker 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 →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Hairy Woodpecker has surged in Illinois: up 136% on the route-weighted index since 1968.

Hairy Woodpecker Population Forecast in Illinois

If the recent trend holds, Hairy Woodpecker in Illinois is projected to fall about 25% by 2029 — from 0.37 in 2024 to a central estimate of 0.28 (95% range 0.11–0.45). A 5-year backtest shows a typical error of ±28.8%, with 80% of held-out values landing inside the 95% band.

-25%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 →
0.28Projected 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 →
0.11–0.4595% 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 →
±28.8%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, Hairy Woodpecker in Illinois is projected to fall about 25% by 2029 — from 0.37 in 2024 to a central estimate of 0.28 (95% range 0.11–0.45). A 5-year backtest shows a typical error of ±28.8%, with 80% 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 →
20250.270.100.44
20260.270.110.44
20270.280.110.44
20280.280.110.45
20290.280.110.45

Hairy Woodpecker Survey Routes in Illinois

Routes recording Hairy Woodpecker 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 →
Belleview520241966
Newark419921992
Belknap420221970
Bremen320241970
Cave In Rock320231993
New Lenox220131971
Stillwell220231976
Dailey220221985
Milford219971997
Pawnee220231967
Humboldt220241982
St Morgan220221967
Pulaski220241971
Delwood220211971
Beaverdam Lk220231970
Sandusky220221993
Lake Summerset220192001
Yorkville220082008
Dudleyville220212004
Guilford120221969
Mill Creek120241975
Holcomb119951980
Cherry Val119901980
Barrington120121971
Itasca120241974

Hairy Woodpecker Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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