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

Brewer's Sparrow Population Trend in Washington

All statesArid-land birds

Brewer's Sparrow in Washington has surged: up 398% on the route-weighted index since 1970.

+398%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 →
37Routes 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 Brewer's 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 →

Brewer's Sparrow has surged in Washington: up 398% on the route-weighted index since 1970.

Brewer's Sparrow Population Forecast in Washington

If the recent trend holds, Brewer's Sparrow in Washington is projected to rise about 11% by 2030 — from 1.5 in 2025 to a central estimate of 1.7 (95% range 0.00–4.2). A 5-year backtest shows a typical error of ±94.8%, with 100% of held-out values landing inside the 95% band.

+11%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 →
1.7Projected 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 →
0.00–4.295% 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 →
±94.8%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, Brewer's Sparrow in Washington is projected to rise about 11% by 2030 — from 1.5 in 2025 to a central estimate of 1.7 (95% range 0.00–4.2). A 5-year backtest shows a typical error of ±94.8%, 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 →
20261.60.004.1
20271.60.004.1
20281.60.004.1
20291.60.004.1
20301.70.004.2

Brewer's Sparrow Survey Routes in Washington

Routes recording Brewer's 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 →
Pomona2419991998
Selah2320252000
Ellensburg1920251981
Moses Coulee1720251993
Bickleton820191990
Asotin420141971
Arid Land Er319961989
Ewan 2320252023
Tonasket320181982
Horn Rapids320112008
Keystone320251994
Odessa320251993
Hanford Site219961994
Twisp220081972
Brewster220181979
Winthrop219901990
Sulphur220141997
Quincy220231985
Wilbur220191989
Nighthawk220251992
Cloverland220242024
Chewelah119921992
Turnbull Nwr120072007
L Pend O Nwr120011999
Moses Lake120211973

Brewer's Sparrow Population Trend in Other States

arizonacaliforniacoloradoidahokansasmontananebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotatexasutahwyoming

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