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Species · Illinois · BBS 2025 Release · 1966–2024

Rose-breasted Grosbeak Population Trend in Illinois

All statesGeneralists

Rose-breasted Grosbeak in Illinois has surged: up 97% on the route-weighted index since 1968.

+97%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 →
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 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 97% 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 18% by 2029 — from 2.3 in 2024 to a central estimate of 1.9 (95% range 1.4–2.4). A 5-year backtest shows a typical error of ±9%, with 80% of held-out values landing inside the 95% band.

-18%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 →
1.9Projected 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 →
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 →
±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, Rose-breasted Grosbeak in Illinois is projected to fall about 18% by 2029 — from 2.3 in 2024 to a central estimate of 1.9 (95% range 1.4–2.4). A 5-year backtest shows a typical error of ±9%, 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 →
20251.81.32.3
20261.81.32.3
20271.81.32.4
20281.91.32.4
20291.91.42.4

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 →
Eubanks1920242001
Guilford1320231967
Payson1120242000
Bradbury1020241973
Terre Haute920241966
Chandlervill820241971
Sherrard720241993
Sheffield620241966
Buda620231980
Williamsfld620241974
Cameron620241971
Deer Creek620241967
Alden620232019
Mill Creek520241967
Atkinson420241966
Putnam420241967
Stillwell420241971
Rosamond420241973
Olney420071984
Caledonia420241994
Clayton420242001
Concord West420232002
Kell420242001
Holcomb320241971
Barrington320081992

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 2026-05-22.