BirdAnalyst
Species · BCR 11 · BBS 2026 Release · 1966–2025

Brewer's Sparrow In Prairie Potholes

All regionsPrairie PotholesArid-land birds

Brewer's Sparrow in Prairie Potholes has surged: up 119% on the route-weighted index since 1972.

+119%Since 1972TrendPercent 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 →
19Routes 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 →
52YearsYears 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 surged in Prairie Potholes: up 118% on the route-weighted index since 1972.

Brewer's Sparrow In Prairie Potholes Population Forecast

If the recent trend holds, Brewer's Sparrow in Prairie Potholes is projected to stay roughly flat through 2030, near 0.38 (95% range 0.04–0.72). A 5-year backtest shows a typical error of ±13.7%, with 100% of held-out values landing inside the 95% band.

+1%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 →
0.38Projected 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 →
0.04–0.7295% 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 →
±13.7%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 Prairie Potholes is projected to stay roughly flat through 2030, near 0.38 (95% range 0.04–0.72). A 5-year backtest shows a typical error of ±13.7%, 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 →
20260.370.030.70
20270.370.030.71
20280.370.030.71
20290.380.040.72
20300.380.040.72

Routes In Prairie Potholes

Routes recording Brewer's Sparrow in Prairie Potholes.
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 →
ChinookMONTANA132025
HarlemMONTANA82021
MaltaMONTANA82025
OswegoMONTANA42001
VirgelleMONTANA32025
GildfordMONTANA22016
Ester LakeMONTANA22025
LambertMONTANA22022
Hay LakeMONTANA12021
SunburstMONTANA12003
ClevelandMONTANA12025
GlasgowMONTANA12021
RedstoneMONTANA12022
Great FallsMONTANA11988
WhitlashMONTANA12024
ShelbyMONTANA12025
SacoMONTANA12019
GlentanaMONTANA12015
Wolf PointMONTANA12018

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