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Species · Montana · BBS 2026 Release · 1966–2025

Black-headed Grosbeak Population Trend in Montana

All statesForest birds

Black-headed Grosbeak in Montana has surged: up 376% on the route-weighted index since 1972.

+376%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 →
77Routes 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 →
55YearsYears 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 375% 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 25% by 2030 — from 0.95 in 2025 to a central estimate of 1.2 (95% range 0.89–1.5). A 5-year backtest shows a typical error of ±13.3%, with 100% of held-out values landing inside the 95% band.

+25%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 →
1.2Projected 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 →
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 →
±13.3%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 25% by 2030 — from 0.95 in 2025 to a central estimate of 1.2 (95% range 0.89–1.5). A 5-year backtest shows a typical error of ±13.3%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20261.10.821.4
20271.10.841.4
20281.20.861.5
20291.20.881.5
20301.20.891.5

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 →
Reed Point1020251978
Woodman720251975
Brandenberg720251972
Ninemile720251993
Savage620191969
Clinton620241975
Highwood520251990
Hebgen Lake520252017
Painted Rock420221994
Noxon420231998
Red Rock320251977
Fish Creek320241995
St Xavier 2320182017
East Glacier Park320252015
Clancy320242015
Miles City320242015
Victor320251993
Fort Logan320222018
Kalispell220251982
St Mary220081973
Glasgow220091995
Sula220231986
Willow Creek219721972
Thompson Riv220211995
Skalkho-Rye220152015

Black-headed Grosbeak Population Trend in Other States

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