BirdAnalyst
Species · Montana · BBS 2026 Release · 1966–2025

Brewer's Blackbird Population Trend in Montana

All statesGeneralists

Brewer's Blackbird in Montana has fallen sharply: down 55% on the route-weighted index since 1970.

-55%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 →
108Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Brewer's Blackbird 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 →

Brewer's Blackbird has fallen sharply in Montana: down 54% on the route-weighted index since 1970.

Brewer's Blackbird Population Forecast in Montana

If the recent trend holds, Brewer's Blackbird in Montana is projected to fall about 32% by 2030 — from 16 in 2025 to a central estimate of 11 (95% range 1.9–20). A 5-year backtest shows a typical error of ±29.9%, with 100% of held-out values landing inside the 95% band.

-32%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 →
11Projected 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 →
1.9–2095% 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 →
±29.9%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, Brewer's Blackbird in Montana is projected to fall about 32% by 2030 — from 16 in 2025 to a central estimate of 11 (95% range 1.9–20). A 5-year backtest shows a typical error of ±29.9%, 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 →
2026123.021
2027122.721
2028122.421
2029112.120
2030111.920

Brewer's Blackbird Survey Routes in Montana

Routes recording Brewer's Blackbird 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 →
Twin Bridges10219761968
St Mary10020081968
Whitlash6720242009
Leroy5220251970
St. Mary 24820252009
Savage4320251969
Augusta4220251976
Freeman Creek4220162015
Albion4120251982
Wolf Creek4120252015
Fort Logan4120252018
Sun River4020252015
Saco3920252015
Hay Lake3720251988
Glen3720251977
Lindsay3720242015
Harlem3620211968
Raynesford3420252016
Wheat Basin3220252017
Elliston3120251968
Cleveland3020251979
Polson2920251972
Great Falls2920251972
Hehn Draw2820252016
Threemile Wa2820251993

Brewer's Blackbird Population Trend in Other States

arizonacaliforniacoloradoidahoindianamichiganminnesotanebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotatexasutahwashingtonwisconsinwyoming

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