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Species · Washington · BBS 2025 Release · 1966–2024

Nashville Warbler Population Trend in Washington

All statesForest birds

Nashville Warbler in Washington has surged: up 928% on the route-weighted index since 1970.

+928%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 →
54Routes 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 Nashville 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 →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Nashville Warbler has surged in Washington: up 928% on the route-weighted index since 1970.

Nashville Warbler Population Forecast in Washington

If the recent trend holds, Nashville Warbler in Washington is projected to rise about 29% by 2029 — from 3.3 in 2024 to a central estimate of 4.2 (95% range 3.1–5.3). A 5-year backtest shows a typical error of ±30.2%, with 100% of held-out values landing inside the 95% band.

+29%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 →
4.2Projected 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 →
3.1–5.395% 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 →
±30.2%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, Nashville Warbler in Washington is projected to rise about 29% by 2029 — from 3.3 in 2024 to a central estimate of 4.2 (95% range 3.1–5.3). A 5-year backtest shows a typical error of ±30.2%, 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 →
20254.02.95.1
20264.02.95.1
20274.13.05.2
20284.23.15.2
20294.23.15.3

Nashville Warbler Survey Routes in Washington

Routes recording Nashville 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. Adams2720241995
Cusick2320241982
Lake Chelan1820241988
Snowden1720241971
Rimrock1620241981
Sullivan Lk1619991999
Leavenworth1420241981
L. Wenatchee1220241993
Mt. Adams1220241994
Sullivan Lake 2820242000
Omak Creek820241996
Ronald720241973
Mazama720221993
Twisp620241969
Twin Lakes620241984
Curlew620131993
Blewett Pass520241992
Keller420071968
Chewelah420211977
L Pend O Nwr420241995
Laurier420222000
Newhalem320241971
Ardenvoir319871983
Cougar320231983
Kendall320161984

Nashville Warbler Population Trend in Other States

californiaconnecticutidahomainemarylandmassachusettsmichiganminnesotamontananew-hampshirenew-jerseynew-yorknorth-dakotaoregonpennsylvaniarhode-islandvermontvirginiawest-virginiawisconsin

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