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Species · Washington · BBS 2025 Release · 1966–2024

Cassin's Vireo Population Trend in Washington

All statesForest birds

Cassin's Vireo in Washington has edged down: down 14% on the route-weighted index since 1970.

-14%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 →
75Routes 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 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 stay roughly flat through 2029, near 2.0 (95% range 1.0–3.0). A 5-year backtest shows a typical error of ±13.1%, with 100% of held-out values landing inside the 95% band.

+9%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 →
2.0Projected 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 →
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 →
±13.1%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, Cassin's Vireo in Washington is projected to stay roughly flat through 2029, near 2.0 (95% range 1.0–3.0). A 5-year backtest shows a typical error of ±13.1%, 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 →
20252.00.953.0
20262.00.973.0
20272.00.983.0
20282.01.003.0
20292.01.03.0

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
Cusick2020241982
Omak Creek1420241996
E. Mt. Adams1020241995
Deer Park1020151996
Sullivan Lk919991999
Rimrock720241969
Carlton720221992
Camas620091977
Laurier620221996
Keller520071968
Snowden520241983
Ronald520241973
Curlew520131993
L. Wenatchee520241993
L Pend O Nwr420241995
Twin Lakes420241985
Leavenworth420241982
Packwood420231977
Spring Lake420241982
Newhalem320241968
Twisp320241970
Chewelah320211977
Kamilche320191968
Ardenvoir319871970

Cassin's Vireo Population Trend in Other States

alaskacaliforniaidahomontanaoregon

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