BirdAnalyst
Species · Washington · BBS 2026 Release · 1966–2025

Vesper Sparrow Population Trend in Washington

All statesGrassland birds

Vesper Sparrow in Washington has surged: up 159% on the route-weighted index since 1970.

+159%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 →
57Routes 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 Vesper Sparrow 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 →

Vesper Sparrow has surged in Washington: up 159% on the route-weighted index since 1970.

Vesper Sparrow Population Forecast in Washington

If the recent trend holds, Vesper Sparrow in Washington is projected to stay roughly flat through 2030, near 3.7 (95% range 1.7–5.8). A 5-year backtest shows a typical error of ±52.9%, with 100% of held-out values landing inside the 95% band.

+9%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 →
3.7Projected 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 →
1.7–5.895% 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 →
±52.9%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, Vesper Sparrow in Washington is projected to stay roughly flat through 2030, near 3.7 (95% range 1.7–5.8). A 5-year backtest shows a typical error of ±52.9%, 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 →
20263.61.65.7
20273.61.65.7
20283.71.65.7
20293.71.75.8
20303.71.75.8

Vesper Sparrow Survey Routes in Washington

Routes recording Vesper Sparrow 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 →
Harrington3620121977
Moses Coulee3420251994
Selah3120252000
Pomona2119991998
Ewan2120191983
Odessa2020251993
Wilbur1620251983
Keystone1320251994
Cloverland1320251993
Pomeroy1220241992
Ellensburg1020251981
Lake Chelan820251988
Ewan 2720252024
L Pend O Nwr720241997
Omak Creek720242007
Turnbull Nwr620211993
Deer Park620151994
Brewster520181977
Asotin520251971
Hatton519941992
Bickleton420171996
Nighthawk420251993
Arid Land Er319961988
Reardan320241968
Winthrop320211988

Vesper Sparrow Population Trend in Other States

arizonacaliforniacoloradoconnecticutdelawareidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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