BirdAnalyst
Species · Montana · BBS 2025 Release · 1966–2024

Evening Grosbeak Population Trend in Montana

All statesGeneralists

Evening Grosbeak in Montana has collapsed: down 92% on the route-weighted index since 1970.

-92%Since 1970TrendPercent 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 →
44Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Evening 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 declinecomputed 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 →

Evening Grosbeak has collapsed in Montana: down 92% on the route-weighted index since 1970.

Evening Grosbeak Population Forecast in Montana

If the recent trend holds, Evening Grosbeak in Montana is projected to fall about 100% by 2029 — from 0.80 in 2024 to a central estimate of 0.00 (95% range 0.00–5.9). A 5-year backtest shows a typical error of ±318.4%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–5.995% 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 →
±318.4%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, Evening Grosbeak in Montana is projected to fall about 100% by 2029 — from 0.80 in 2024 to a central estimate of 0.00 (95% range 0.00–5.9). A 5-year backtest shows a typical error of ±318.4%, 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 →
20250.000.005.9
20260.000.005.9
20270.000.005.9
20280.000.005.9
20290.000.005.9

Evening Grosbeak Survey Routes in Montana

Routes recording Evening 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 →
Elevation Mt2820242009
Greenoagh 31720242012
Greenoagh 21320112011
Threemile Wa820231994
Brandenberg819681968
Painted Rock820191992
Skalkho-Rye720192011
Elliston620231972
Fish Creek620241995
Wise River620241993
Whitefish Lake520192016
Clancy520222016
Libby Dam419951979
Victor420211993
Polson419971997
Woodman420241968
Boulder419781978
Shawmut419991999
Chestnut420221969
Swan Lake420242015
Logan Pass320101995
Augusta320131989
Cramer Creek220192010
Inside Road220151994
Beaverhead219901990

Evening Grosbeak Population Trend in Other States

arizonacaliforniacoloradoconnecticutidahomainemassachusettsmichiganminnesotanevadanew-hampshirenew-mexiconew-yorkoregonsouth-dakotautahvermontwashingtonwisconsinwyoming

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