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

Black-billed Magpie Population Trend in Idaho

All statesGeneralists

Black-billed Magpie in Idaho has fallen sharply: down 60% on the route-weighted index since 1970.

-60%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 →
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 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 60% 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 fall about 28% by 2029 — from 13 in 2024 to a central estimate of 9.0 (95% range 0.00–22). A 5-year backtest shows a typical error of ±29.3%, with 100% of held-out values landing inside the 95% band.

-28%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 →
9.0Projected 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 →
0.00–2295% 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 →
±29.3%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-billed Magpie in Idaho is projected to fall about 28% by 2029 — from 13 in 2024 to a central estimate of 9.0 (95% range 0.00–22). A 5-year backtest shows a typical error of ±29.3%, 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 →
20259.50.0023
20269.40.0022
20279.30.0022
20289.10.0022
20299.00.0022

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
Picabo6520211988
Springfield5420181969
Baker4520241974
Bates4320231988
Preston2420231988
Mud Lake2320231988
Iron Springs1920241988
Blacks Creek1720171968
Henry1619831973
Joel1520241989
Tractor Flat1420241985
Pasadena Val1320161987
Dubois1220241969
Triangle1220241985
Squirrel1120241971
Ririe1120231971
Almo1020231988
Daniels Res920191988
Coolin820241986
Salmon River820211988
Challis720241975
Craters720181979

Black-billed Magpie Population Trend in Other States

alaskaarizonacaliforniacoloradokansasminnesotamontananebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotautahwashingtonwyoming

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