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

Brewer's Sparrow Population Trend in Oregon

All statesArid-land birds

Brewer's Sparrow in Oregon has surged: up 175% on the route-weighted index since 1970.

+175%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 →
76Routes 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 Brewer's Sparrow Trends in OregonNotable 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 Oregon: up 175% on the route-weighted index since 1970.

Brewer's Sparrow Population Forecast in Oregon

If the recent trend holds, Brewer's Sparrow in Oregon is projected to fall about 25% by 2030 — from 10 in 2025 to a central estimate of 7.8 (95% range 0.00–21). A 5-year backtest shows a typical error of ±13%, with 100% of held-out values landing inside the 95% band.

-25%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 →
7.8Projected 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 →
0.00–2195% 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%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 Oregon is projected to fall about 25% by 2030 — from 10 in 2025 to a central estimate of 7.8 (95% range 0.00–21). A 5-year backtest shows a typical error of ±13%, 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 →
20268.30.0021
20278.20.0021
20288.10.0021
20297.90.0021
20307.80.0021

Brewer's Sparrow Survey Routes in Oregon

Routes recording Brewer's Sparrow in Oregon.
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 →
Wagontire15520251968
Princeton14419851972
Blitzen 28820251994
Blitzen8619931971
Green Mtn.8220251994
Clover Creek7520251972
Willow Spg7119711969
Lookout Lake6719941985
Buchanan6620251971
Battle Mtn6620251985
Crowley6020251983
Fandango Can5920251977
Blizzard Gap4720251984
Malheur Res.4620232022
Crooked Riv.4420251994
Crane4020241993
Fish Lake3920251972
Flook Lake3920251994
Silver Creek3420251984
Malheur Nwr3220221986
Three Forks3120252003
Madras2820251997
Donnelly2720061995
Lakeview1520251996
Trout Creek1420252005

Brewer's Sparrow Population Trend in Other States

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