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

Black-billed Magpie Population Trend in Montana

All statesGeneralists

Black-billed Magpie in Montana has declined: down 31% on the route-weighted index since 1970.

-31%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 →
93Routes 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 Black-billed Magpie 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 →

No notable trend signals for Black-billed Magpie in Montana. See the full index history below.

Black-billed Magpie Population Forecast in Montana

If the recent trend holds, Black-billed Magpie in Montana is projected to fall about 31% by 2029 — from 10 in 2024 to a central estimate of 7.0 (95% range 1.8–12). A 5-year backtest shows a typical error of ±18.1%, with 100% of held-out values landing inside the 95% band.

-31%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 →
7.0Projected 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 →
1.8–1295% 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 →
±18.1%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-billed Magpie in Montana is projected to fall about 31% by 2029 — from 10 in 2024 to a central estimate of 7.0 (95% range 1.8–12). A 5-year backtest shows a typical error of ±18.1%, 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 →
20257.11.912
20267.11.812
20277.11.812
20287.01.812
20297.01.812

Black-billed Magpie Survey Routes in Montana

Routes recording Black-billed Magpie 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 →
Clyde Park8720242018
Chestnut5520241968
Fort Logan4920242018
Polson4320241972
Glen3920241977
Reed Point3820241977
Church Hill3720242017
Heart Butte3620242015
Redstone3520241968
Victor3420241993
Lima3220241994
Highwood3020241968
Ninemile2720241993
Laurel2620221968
Willow Creek 22520241982
Cramer Creek2520162008
Willow Creek2419811972
St. Mary 22320242009
Kalispell2220241968
Cleveland2220241979
Freeman Creek2120162015
Pablo Res.1920241995
St Mary1820081968
Twin Bridges1819761968
Wolf Creek1820222015

Black-billed Magpie Population Trend in Other States

alaskaarizonacaliforniacoloradoidahokansasminnesotanebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotautahwashingtonwyoming

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