BirdAnalyst
Species · BCR 9 · BBS 2026 Release · 1966–2025

Brewer's Sparrow In Great Basin

All regionsGreat BasinArid-land birds

Brewer's Sparrow in Great Basin has risen sharply: up 66% on the route-weighted index since 1970.

+66%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 →
217Routes In RegionSurvey 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 SignalsNotable 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 risen sharply in Great Basin: up 66% on the route-weighted index since 1970.

Brewer's Sparrow In Great Basin Population Forecast

If the recent trend holds, Brewer's Sparrow in Great Basin is projected to stay roughly flat through 2030, near 16 (95% range 7.1–25). A 5-year backtest shows a typical error of ±40.9%, with 100% of held-out values landing inside the 95% band.

+10%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 →
16Projected 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 →
7.1–2595% 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 →
±40.9%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, Brewer's Sparrow in Great Basin is projected to stay roughly flat through 2030, near 16 (95% range 7.1–25). A 5-year backtest shows a typical error of ±40.9%, 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 →
2026167.325
2027167.325
2028167.225
2029167.225
2030167.125

Routes In Great Basin

Routes recording Brewer's Sparrow in Great Basin.
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 →
WagontireOREGON1552025
PrincetonOREGON1441985
Charleston ReservoirNEVADA1382024
HawthorneNEVADA1062001
Dinner StaNEVADA991993
Blitzen 2OREGON882025
BlitzenOREGON861993
Green Mtn.OREGON822025
Bald Mtn.NEVADA772025
MizpahNEVADA752024
Willow SpgOREGON711971
RanchograndeNEVADA672024
Lookout LakeOREGON671994
RavendaleCALIFORNIA662025
BuchananOREGON662025
Battle MtnOREGON662025
BodieCALIFORNIA612025
Walker CanNEVADA602024
Sheldon NwrNEVADA602019
CrowleyOREGON602025
Ruby ValleyNEVADA592001
Fandango CanOREGON592025
DuboisIDAHO582025
Crowley LakeCALIFORNIA542025
Tractor FlatIDAHO512025

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