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

Scarlet Tanager Population Trend in Illinois

All statesGeneralists

Scarlet Tanager in Illinois has surged: up 98% on the route-weighted index since 1968.

+98%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 →
87Routes 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 Scarlet Tanager 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 →

Scarlet Tanager has surged in Illinois: up 98% on the route-weighted index since 1968.

Scarlet Tanager Population Forecast in Illinois

If the recent trend holds, Scarlet Tanager in Illinois is projected to rise about 74% by 2029 — from 0.23 in 2024 to a central estimate of 0.40 (95% range 0.23–0.56). A 5-year backtest shows a typical error of ±36.2%, with 80% of held-out values landing inside the 95% band.

+74%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 →
0.40Projected 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 →
0.23–0.5695% 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 →
±36.2%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, Scarlet Tanager in Illinois is projected to rise about 74% by 2029 — from 0.23 in 2024 to a central estimate of 0.40 (95% range 0.23–0.56). A 5-year backtest shows a typical error of ±36.2%, 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 →
20250.380.220.54
20260.390.220.55
20270.390.230.55
20280.390.230.56
20290.400.230.56

Scarlet Tanager Survey Routes in Illinois

Routes recording Scarlet Tanager 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 →
Barrington319951993
Birds320221980
Guilford220221969
Putnam220041981
Dailey220211988
Melrose219951994
Pawnee220181968
Janesville220231973
Bremen220241969
Delwood220241970
Brownville220191993
Sandusky220231993
Cave In Rock220241993
Royalton220192001
Mill Creek120181966
Holcomb119821982
Cherry Val120021984
Itasca119971989
Atkinson120211995
Geneseo120001987
Sheffield120191971
Buda120191997
Compton119841968
Streator119811981
Wayne120231981

Scarlet Tanager Population Trend in Other States

alabamaarkansasconnecticutdelawaregeorgiaindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseevermontvirginiawest-virginiawisconsin

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