BirdAnalyst
Species · Illinois · BBS 2026 Release · 1966–2025

Common Yellowthroat Population Trend in Illinois

All statesForest birds

Common Yellowthroat in Illinois has surged: up 132% on the route-weighted index since 1968.

+132%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 →
105Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Common Yellowthroat 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 →

Common Yellowthroat has surged in Illinois: up 132% on the route-weighted index since 1968.

Common Yellowthroat Population Forecast in Illinois

If the recent trend holds, Common Yellowthroat in Illinois is projected to fall about 24% by 2030 — from 16 in 2025 to a central estimate of 12 (95% range 8.2–16). A 5-year backtest shows a typical error of ±33.9%, with 0% of held-out values landing inside the 95% band.

-24%Change by 2030TrendPercent 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 →
12Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
8.2–1695% 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 →
±33.9%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, Common Yellowthroat in Illinois is projected to fall about 24% by 2030 — from 16 in 2025 to a central estimate of 12 (95% range 8.2–16). A 5-year backtest shows a typical error of ±33.9%, with 0% of held-out values landing inside the 95% band.19662030
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 →
2026128.016
2027128.116
2028128.116
2029128.216
2030128.216

Common Yellowthroat Survey Routes in Illinois

Routes recording Common Yellowthroat 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 →
Belknap5020251970
Bradbury4820251970
Brownville4820251993
Brnt Prairie4320251976
Sandusky4020231993
Beaverdam Lk3820231970
Janesville3720251972
Pulaski3520251970
Marshall3320252001
Kell3220252001
Belleview3120251966
Bremen2920251969
Martinsville2820251970
Guilford2720231967
Delwood2620251970
Wayne2520251966
Melrose2519991973
Mt Vernon2520251971
Atkinson2420241966
Sherrard2420251994
York2320251993
Athensville2220251971
Eubanks2220252001
Putnam2120241967
Sheffield2120241966

Common Yellowthroat Population Trend in Other States

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

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.