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

Black-billed Magpie Population Trend in Idaho

All statesGeneralists

Black-billed Magpie in Idaho has fallen sharply: down 69% on the route-weighted index since 1970.

-69%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 →
52Routes 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 Black-billed Magpie Trends in IdahoNotable 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 →

Black-billed Magpie has fallen sharply in Idaho: down 69% on the route-weighted index since 1970.

Black-billed Magpie Population Forecast in Idaho

If the recent trend holds, Black-billed Magpie in Idaho is projected to rise about 75% by 2030 — from 4.8 in 2025 to a central estimate of 8.4 (95% range 0.00–21). A 5-year backtest shows a typical error of ±34.1%, with 100% of held-out values landing inside the 95% band.

+75%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 →
8.4Projected 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 →
0.00–2195% 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 →
±34.1%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 Idaho is projected to rise about 75% by 2030 — from 4.8 in 2025 to a central estimate of 8.4 (95% range 0.00–21). A 5-year backtest shows a typical error of ±34.1%, 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 →
20269.00.0022
20278.80.0022
20288.70.0022
20298.50.0021
20308.40.0021

Black-billed Magpie Survey Routes in Idaho

Routes recording Black-billed Magpie in Idaho.
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 →
Pocatello11020191979
Leadore7920241974
Cedar Hill7120241989
Springfield5420181969
Baker4520241974
Bates4320231988
Mud Lake3120251988
Ririe2620251971
Preston2420231988
Iron Springs1920241988
Blacks Creek1720171968
Squirrel1620251971
Henry1619831973
Picabo1620251988
Joel1520241989
Cabarton1520241986
Pasadena Val1320161987
Salmon River1020251988
Triangle920251985
Naples820251997
Tractor Flat720251985
Craters720181979
Glenns Ferry719861968
Coolin720251986
Grangeville619861986

Black-billed Magpie Population Trend in Other States

alaskaarizonacaliforniacoloradokansasminnesotamontananebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotautahwashingtonwyoming

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