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Species · Washington · BBS 2025 Release · 1966–2024

MacGillivray's Warbler Population Trend in Washington

All statesForest birds

MacGillivray's Warbler in Washington has declined: down 27% on the route-weighted index since 1970.

-27%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 →
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 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 38% by 2029 — from 5.3 in 2024 to a central estimate of 3.3 (95% range 1.1–5.4). A 5-year backtest shows a typical error of ±31.1%, with 60% of held-out values landing inside the 95% band.

-38%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 →
3.3Projected 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 →
1.1–5.495% 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 →
±31.1%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, MacGillivray's Warbler in Washington is projected to fall about 38% by 2029 — from 5.3 in 2024 to a central estimate of 3.3 (95% range 1.1–5.4). A 5-year backtest shows a typical error of ±31.1%, with 60% 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 →
20253.41.25.5
20263.31.25.5
20273.31.25.5
20283.31.25.5
20293.31.15.4

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 →
Snowden2820241981
E. Mt. Adams2820241995
Newhalem2620241968
Blewett Pass2520241992
Glacier1820241975
Mt. Adams1620241994
Leavenworth1520241981
Lake Chelan1420241988
Cougar1320231968
Rimrock1220241968
Kendall1220241981
Laurier1220221998
Montesand1120241998
Mcchord1120151996
Cusick1020241982
L. Wenatchee1020241993
Cedar Falls920141993
Omak Creek920241996
Cascade Riv920061988
Twin Lakes820241983
Ronald820241973
Mazama820221993
Concrete820242013
White Chuck720241992
Keller620071968

MacGillivray's Warbler Population Trend in Other States

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