BirdAnalyst
Species · BCR 22 · BBS 2026 Release · 1966–2025

Blue Grosbeak In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieForest birds

Blue Grosbeak in Eastern Tallgrass Prairie has surged: up 13× on the route-weighted index since 1968.

13×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 →
193Routes In RegionSurvey 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 SignalsNotable 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 →

Blue Grosbeak has surged in Eastern Tallgrass Prairie: up 13× on the route-weighted index since 1968.

Blue Grosbeak In Eastern Tallgrass Prairie Population Forecast

If the recent trend holds, Blue Grosbeak in Eastern Tallgrass Prairie is projected to fall about 24% by 2030 — from 2.7 in 2025 to a central estimate of 2.0 (95% range 1.3–2.7). A 5-year backtest shows a typical error of ±43.6%, 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 →
2.0Projected 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 →
1.3–2.795% 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 →
±43.6%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, Blue Grosbeak in Eastern Tallgrass Prairie is projected to fall about 24% by 2030 — from 2.7 in 2025 to a central estimate of 2.0 (95% range 1.3–2.7). A 5-year backtest shows a typical error of ±43.6%, 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 →
20261.91.22.6
20271.91.22.7
20282.01.32.7
20292.01.32.7
20302.01.32.7

Routes In Eastern Tallgrass Prairie

Routes recording Blue Grosbeak in Eastern Tallgrass Prairie.
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 →
FrankfordMISSOURI332025
FilleyMISSOURI172025
LincolnvilleKANSAS162024
Mt VernonILLINOIS132025
Trading PostKANSAS132025
DanvilleMISSOURI132025
ChandlervillILLINOIS122025
BelleviewILLINOIS122025
JanesvilleILLINOIS122025
FloraILLINOIS122024
DudleyvilleILLINOIS122025
KellILLINOIS112025
RensselaerMISSOURI112025
MadisonMISSOURI112024
Mascoutah LkILLINOIS102025
MarshallILLINOIS102025
OlneyILLINOIS92024
HumboldtKANSAS92022
JamestownILLINOIS82025
RobinsonILLINOIS82023
HuntsvilleMISSOURI82025
EmdenMISSOURI82024
BradburyILLINOIS72025
BeaucoupILLINOIS72025
Duncan MillsILLINOIS72025

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