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Species · Washington · BBS 2026 Release · 1966–2025

MacGillivray's Warbler Population Trend in Washington

All statesForest birds

MacGillivray's Warbler in Washington has edged down: down 24% on the route-weighted index since 1970.

-24%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 →
79Routes 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 MacGillivray's Warbler 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 MacGillivray's Warbler in Washington. See the full index history below.

MacGillivray's Warbler Population Forecast in Washington

If the recent trend holds, MacGillivray's Warbler in Washington is projected to fall about 28% by 2030 — from 4.7 in 2025 to a central estimate of 3.4 (95% range 1.2–5.5). A 5-year backtest shows a typical error of ±32.2%, with 80% of held-out values landing inside the 95% band.

-28%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 →
3.4Projected 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 →
1.2–5.595% 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 →
±32.2%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, MacGillivray's Warbler in Washington is projected to fall about 28% by 2030 — from 4.7 in 2025 to a central estimate of 3.4 (95% range 1.2–5.5). A 5-year backtest shows a typical error of ±32.2%, with 80% 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 →
20263.41.35.6
20273.41.35.6
20283.41.25.6
20293.41.25.5
20303.41.25.5

MacGillivray's Warbler Survey Routes in Washington

Routes recording MacGillivray's Warbler 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 →
E. Mt. Adams3520251995
Blewett Pass2820251992
Glacier1820241975
Snowden1720251981
Mt. Adams1620251994
Leavenworth1520241981
Newhalem1420251968
Cougar1320231968
Ronald1220251973
Laurier1220221998
White Chuck1120251992
Montesand1120241998
Mcchord1120151996
Rimrock1020251968
Twin Lakes920251983
Cedar Falls920141993
Omak Creek920241996
Cascade Riv920061988
Spring Lake820251985
Mazama820221993
Kendall720251981
Hurricane Rg720251992
Keller620071968
Cusick620251982
Curlew620131992

MacGillivray's Warbler Population Trend in Other States

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