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

Brewer's Sparrow Population Trend in Oregon

All statesGeneralists

Brewer's Sparrow in Oregon has surged: up 143% on the route-weighted index since 1970.

+143%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 →
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 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 143% 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 14% by 2029 — from 9.0 in 2024 to a central estimate of 7.8 (95% range 0.00–21). A 5-year backtest shows a typical error of ±13.8%, with 100% of held-out values landing inside the 95% band.

-14%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 →
7.8Projected 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 →
0.00–2195% 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 →
±13.8%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 Oregon is projected to fall about 14% by 2029 — from 9.0 in 2024 to a central estimate of 7.8 (95% range 0.00–21). A 5-year backtest shows a typical error of ±13.8%, 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 →
20258.30.0021
20268.20.0021
20278.00.0021
20287.90.0021
20297.80.0021

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 →
Princeton14419851972
Wagontire13220241968
Blitzen8619931971
Clover Creek8020241972
Fandango Can7420241977
Blitzen 27220241994
Willow Spg7119711969
Lookout Lake6719941985
Blizzard Gap6020241984
Buchanan5120241971
Crowley5020241983
Malheur Res.4620232022
Crane4020241993
Three Forks3420242003
Flook Lake3320241994
Malheur Nwr3220221986
Silver Creek2920241984
Donnelly2720061995
Crooked Riv.2620241994
Madras2220241997
Fish Lake2120241972
Sheaville2020242012
Battle Mtn1420241985
Barnhouse1220241999
Bridgeport920221987

Brewer's Sparrow Population Trend in Other States

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