BirdAnalyst
Species · Washington · BBS 2025 Release · 1966–2024

Brewer's Sparrow Population Trend in Washington

All statesGeneralists

Brewer's Sparrow in Washington has surged: up 302% on the route-weighted index since 1970.

+302%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 →
55YearsYears 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 302% 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 162% by 2029 — from 0.63 in 2024 to a central estimate of 1.7 (95% range 0.00–4.2). A 5-year backtest shows a typical error of ±92.5%, with 100% of held-out values landing inside the 95% band.

+162%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 →
1.7Projected 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 →
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 →
±92.5%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 162% by 2029 — from 0.63 in 2024 to a central estimate of 1.7 (95% range 0.00–4.2). A 5-year backtest shows a typical error of ±92.5%, 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 →
20251.60.004.1
20261.60.004.2
20271.60.004.2
20281.60.004.2
20291.70.004.2

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 →
Selah4020232000
Pomona2419991998
Ellensburg1820241981
Lake Chelan1120191992
Bickleton820191990
Moses Coulee820231993
Odessa820241993
Keystone620241994
Asotin420141971
Nighthawk420231992
Arid Land Er319961989
Tonasket320181982
Horn Rapids320112008
Hanford Site219961994
Twisp220081972
Brewster220181979
Winthrop219901990
Sulphur220141997
Quincy220231985
Wilbur220191989
Cloverland220242024
Chewelah119921992
Turnbull Nwr120072007
Ewan 2120232023
L Pend O Nwr120011999

Brewer's Sparrow Population Trend in Other States

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