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

Black-billed Magpie Population Trend in Washington

All statesGeneralists

Black-billed Magpie in Washington 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 →
56Routes 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 WashingtonNotable 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 Washington. See the full index history below.

Black-billed Magpie Population Forecast in Washington

If the recent trend holds, Black-billed Magpie in Washington is projected to rise about 44% by 2029 — from 3.0 in 2024 to a central estimate of 4.4 (95% range 0.55–8.2). A 5-year backtest shows a typical error of ±61.4%, with 100% of held-out values landing inside the 95% band.

+44%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 →
4.4Projected 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 →
0.55–8.295% 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 →
±61.4%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, Black-billed Magpie in Washington is projected to rise about 44% by 2029 — from 3.0 in 2024 to a central estimate of 4.4 (95% range 0.55–8.2). A 5-year backtest shows a typical error of ±61.4%, 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 →
20254.50.688.3
20264.50.658.3
20274.40.618.3
20284.40.588.2
20294.40.558.2

Black-billed Magpie Survey Routes in Washington

Routes recording Black-billed Magpie in Washington.
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 →
Mesa9020081994
Othello5919911981
Chewelah3920211977
Yakima3720241993
Nighthawk3520241992
Harwood3419971993
Asotin2420241971
Walla Walla2419931993
Wapato2020221971
Moses Lake1920221973
Columbia Nwr1520221992
Pomona1519991998
Ewan1420191983
Ewan 21220242023
Reardan1220241968
Hanford Site1119961988
Harrington920121974
Moses Coulee920231993
Ellensburg820241981
Deer Park720151994
Quincy620241982
Scootney Reservoir620242009
Potholes620231996
Pomeroy620241992
Laurier520221997

Black-billed Magpie Population Trend in Other States

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