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Species · Washington · BBS 2026 Release · 1966–2025

Cassin's Vireo Population Trend in Washington

All statesForest birds

Cassin's Vireo in Washington has held roughly steady: down 10% on the route-weighted index since 1970.

-10%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 →
76Routes 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 Cassin's Vireo 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 Cassin's Vireo in Washington. See the full index history below.

Cassin's Vireo Population Forecast in Washington

If the recent trend holds, Cassin's Vireo in Washington is projected to rise about 12% by 2030 — from 1.8 in 2025 to a central estimate of 2.0 (95% range 1.0–3.0). A 5-year backtest shows a typical error of ±12.9%, with 100% of held-out values landing inside the 95% band.

+12%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 →
2.0Projected 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 →
1.0–3.095% 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 →
±12.9%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, Cassin's Vireo in Washington is projected to rise about 12% by 2030 — from 1.8 in 2025 to a central estimate of 2.0 (95% range 1.0–3.0). A 5-year backtest shows a typical error of ±12.9%, 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 →
20262.00.963.0
20272.00.983.0
20282.00.993.0
20292.01.03.0
20302.01.03.0

Cassin's Vireo Survey Routes in Washington

Routes recording Cassin's Vireo 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 →
Ewan3219951995
Cusick2220251982
Omak Creek1420241996
Deer Park1020151996
Twin Lakes920251985
Sullivan Lk919991999
E. Mt. Adams820251995
Spring Lake720251982
Carlton720221992
Camas620091977
Keller520071968
Rimrock520251969
Snowden520241983
Sullivan Lake 2520252000
Curlew520131993
Newhalem420251968
L Pend O Nwr420241995
Leavenworth420241982
Packwood420231977
Blewett Pass420251992
Twisp320241970
Chewelah320211977
Kamilche320191968
Ardenvoir319871970
Bunker Hill320071974

Cassin's Vireo Population Trend in Other States

alaskacaliforniaidahomontanaoregon

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