BirdAnalyst
Species · BCR 16 · BBS 2025 Release · 1966–2024

Brewer's Sparrow In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauGeneralists

Brewer's Sparrow in Southern Rockies / Colorado Plateau has surged: up 106% on the route-weighted index since 1970.

+106%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 →
182Routes 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 →
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 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 Southern Rockies / Colorado Plateau: up 106% on the route-weighted index since 1970.

Brewer's Sparrow In Southern Rockies / Colorado Plateau Population Forecast

If the recent trend holds, Brewer's Sparrow in Southern Rockies / Colorado Plateau is projected to rise about 20% by 2029 — from 5.8 in 2024 to a central estimate of 6.9 (95% range 2.6–11). A 5-year backtest shows a typical error of ±30%, with 100% of held-out values landing inside the 95% band.

+20%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 →
6.9Projected 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 →
2.6–1195% 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 →
±30%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 Southern Rockies / Colorado Plateau is projected to rise about 20% by 2029 — from 5.8 in 2024 to a central estimate of 6.9 (95% range 2.6–11). A 5-year backtest shows a typical error of ±30%, 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 →
20256.72.511
20266.82.511
20276.82.511
20286.92.611
20296.92.611

Routes In Southern Rockies / Colorado Plateau

Routes recording Brewer's Sparrow in Southern Rockies / Colorado Plateau.
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 →
WaldenCOLORADO802024
DinosaurCOLORADO692024
M Warner ResUTAH532024
Black Sulphur CrCOLORADO432024
BeckUTAH401987
AltonahUTAH402015
Wray GulchCOLORADO382023
AngoraCOLORADO352024
VernalUTAH352018
YampaCOLORADO342023
Lost Cr. ResUTAH342018
Fish Lake NfUTAH332024
Yellowjacket PassCOLORADO322024
BlandingUTAH312023
PiedraCOLORADO301999
Wilson CreekCOLORADO282024
Baxter PassCOLORADO282024
PowderhornCOLORADO272023
AntonitoCOLORADO272004
Moon Lake 2UTAH272023
Ant Flat-Ogden CanUTAH262023
Uintah NfUTAH251994
Piceance BasinCOLORADO222012
MoscaCOLORADO212024
Canyon RimsUTAH202024

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