BirdAnalyst
Species · BCR 22 · BBS 2025 Release · 1966–2024

Blue Grosbeak In Eastern Tallgrass Prairie

All regionsEastern Tallgrass PrairieGeneralists

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 →
187Routes 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 →
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 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.

Forecast

If the recent trend holds, Blue Grosbeak in Eastern Tallgrass Prairie is projected to fall about 38% by 2029 — from 3.1 in 2024 to a central estimate of 1.9 (95% range 1.3–2.6). A 5-year backtest shows a typical error of ±38%, with 20% of held-out values landing inside the 95% band.

-38%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 →
1.3–2.695% 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 →
±38%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 38% by 2029 — from 3.1 in 2024 to a central estimate of 1.9 (95% range 1.3–2.6). A 5-year backtest shows a typical error of ±38%, 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 →
20251.81.12.5
20261.91.22.5
20271.91.22.6
20281.91.22.6
20291.91.32.6

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 →
FrankfordMISSOURI262024
FilleyMISSOURI202024
LincolnvilleKANSAS162024
Mt VernonILLINOIS142024
KellILLINOIS142024
AuburnMISSOURI132024
BelleviewILLINOIS122024
JanesvilleILLINOIS122024
FloraILLINOIS122024
BucyrusKANSAS122024
DanvilleMISSOURI122024
MarshallILLINOIS112024
SeveranceKANSAS112024
MadisonMISSOURI112024
HuntsvilleMISSOURI112024
PaysonILLINOIS102024
ReeceKANSAS102024
BradburyILLINOIS92024
OlneyILLINOIS92024
DudleyvilleILLINOIS92024
HumboldtKANSAS92022
Mascoutah LkILLINOIS82024
JamestownILLINOIS82024
RobinsonILLINOIS82023
EmdenMISSOURI82024

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