BirdAnalyst
Species · BCR 11 · BBS 2025 Release · 1966–2024

Brewer's Sparrow In Prairie Potholes

All regionsPrairie PotholesGeneralists

Brewer's Sparrow in Prairie Potholes has surged: up 103% on the route-weighted index since 1972.

+103%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 →
51YearsYears 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 103% 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 rise about 22% by 2029 — from 0.31 in 2024 to a central estimate of 0.38 (95% range 0.04–0.72). A 5-year backtest shows a typical error of ±22.7%, with 100% of held-out values landing inside the 95% band.

+22%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 →
0.38Projected 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 →
0.04–0.7295% 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 →
±22.7%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 rise about 22% by 2029 — from 0.31 in 2024 to a central estimate of 0.38 (95% range 0.04–0.72). A 5-year backtest shows a typical error of ±22.7%, 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 →
20250.360.020.70
20260.370.020.71
20270.370.030.71
20280.370.030.72
20290.380.040.72

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 →
ClevelandMONTANA122024
HarlemMONTANA82021
ShelbyMONTANA62022
MaltaMONTANA52024
OswegoMONTANA42001
Ester LakeMONTANA42023
VirgelleMONTANA22024
GildfordMONTANA22016
ChinookMONTANA22024
LambertMONTANA22022
Hay LakeMONTANA12021
SunburstMONTANA12003
GlasgowMONTANA12021
RedstoneMONTANA12022
Great FallsMONTANA11988
WhitlashMONTANA12024
SacoMONTANA12019
GlentanaMONTANA12015
Wolf PointMONTANA12018

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