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Species · Montana · BBS 2025 Release · 1966–2024

Black-headed Grosbeak Population Trend in Montana

All statesGeneralists

Black-headed Grosbeak in Montana has surged: up 390% on the route-weighted index since 1972.

+390%Since 1972TrendPercent 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 →
72Routes 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 →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-headed Grosbeak Trends in MontanaNotable 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 →

Black-headed Grosbeak has surged in Montana: up 390% on the route-weighted index since 1972.

Black-headed Grosbeak Population Forecast in Montana

If the recent trend holds, Black-headed Grosbeak in Montana is projected to rise about 16% by 2029 — from 1.0 in 2024 to a central estimate of 1.2 (95% range 0.89–1.5). A 5-year backtest shows a typical error of ±10.6%, with 100% of held-out values landing inside the 95% band.

+16%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 →
1.2Projected 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 →
0.89–1.595% 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 →
±10.6%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, Black-headed Grosbeak in Montana is projected to rise about 16% by 2029 — from 1.0 in 2024 to a central estimate of 1.2 (95% range 0.89–1.5). A 5-year backtest shows a typical error of ±10.6%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20251.10.821.4
20261.10.841.4
20271.20.861.5
20281.20.871.5
20291.20.891.5

Black-headed Grosbeak Survey Routes in Montana

Routes recording Black-headed Grosbeak in Montana.
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 →
Libby Dam1320151982
Kalispell1120241982
East Glacier Park1020242015
St. Mary 2920242011
Chestnut820231968
Hebgen Lake720242017
Arlee620241973
Savage620191969
Clinton620241975
Logan Pass520241980
Reed Point520241978
Brandenberg520191972
Ninemile420241993
Painted Rock420221994
Noxon420231998
St Xavier 2320182017
Pryor Mtn.320232002
Pablo Res.320222000
Fish Creek320241995
Miles City320242015
Chuffey Spring320242016
Fort Logan320222018
St Mary220081973
Glasgow220091995
Threemile Wa220241993

Black-headed Grosbeak Population Trend in Other States

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