BirdAnalyst
Species · Illinois · BBS 2025 Release · 1966–2024

Common Yellowthroat Population Trend in Illinois

All statesForest birds

Common Yellowthroat in Illinois has surged: up 122% on the route-weighted index since 1968.

+122%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 →
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 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 122% 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 23% by 2029 — from 15 in 2024 to a central estimate of 12 (95% range 8.0–15). A 5-year backtest shows a typical error of ±31.2%, with 20% of held-out values landing inside the 95% band.

-23%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 →
12Projected 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 →
8.0–1595% 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 →
±31.2%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 23% by 2029 — from 15 in 2024 to a central estimate of 12 (95% range 8.0–15). A 5-year backtest shows a typical error of ±31.2%, with 20% 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 →
2025117.815
2026127.915
2027127.915
2028127.915
2029128.015

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 →
Belknap4420241970
Brownville4420241993
Sandusky4020231993
Beaverdam Lk3820231970
Brnt Prairie3720241976
Janesville3520241972
Belleview3420241966
Bradbury3320241970
Delwood3320241970
Bremen2820241969
Marshall2820242001
Guilford2720231967
Stillwell2720241971
York2720241993
Royalton2720242001
Melrose2519991973
Alden2520232019
Kell2520242001
Atkinson2420241966
Pulaski2420241970
Humboldt2320241970
Karnak2220242001
Putnam2120241967
Sheffield2120241966
Robinson2020231970

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 2026-05-22.