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

Rose-breasted Grosbeak Population Trend in Illinois

All statesForest birds

Rose-breasted Grosbeak in Illinois has surged: up 119% on the route-weighted index since 1968.

+119%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 →
98Routes 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 Rose-breasted Grosbeak 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 →

Rose-breasted Grosbeak has surged in Illinois: up 119% on the route-weighted index since 1968.

Rose-breasted Grosbeak Population Forecast in Illinois

If the recent trend holds, Rose-breasted Grosbeak in Illinois is projected to fall about 19% by 2030 — from 2.4 in 2025 to a central estimate of 1.9 (95% range 1.4–2.4). A 5-year backtest shows a typical error of ±13.4%, with 60% of held-out values landing inside the 95% band.

-19%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 →
1.9Projected 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 →
1.4–2.495% 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 →
±13.4%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, Rose-breasted Grosbeak in Illinois is projected to fall about 19% by 2030 — from 2.4 in 2025 to a central estimate of 1.9 (95% range 1.4–2.4). A 5-year backtest shows a typical error of ±13.4%, with 60% 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 →
20261.91.42.4
20271.91.42.4
20281.91.42.4
20291.91.42.4
20301.91.42.4

Rose-breasted Grosbeak Survey Routes in Illinois

Routes recording Rose-breasted Grosbeak 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 →
Guilford1320231967
Eubanks1320252001
Terre Haute920251966
Williamsfld920251974
Clayton920252001
Sherrard820251993
Chandlervill720251971
Concord720251967
Payson720252000
Sheffield620241966
Buda620231980
Deer Creek620241967
Seneca620251997
Camp Point620251993
Humphrey520251972
Bradbury520251973
Mill Creek420251967
Holcomb420251971
Atkinson420241966
Putnam420241967
Bartonville420251973
Bluff Spgs420251970
Pawnee420251972
Olney420071984
Duncan Mills420251994

Rose-breasted Grosbeak Population Trend in Other States

arkansasconnecticutgeorgiaindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseevermontvirginiawest-virginiawisconsinwyoming

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