BirdAnalyst
Species · BCR 16 · BBS 2026 Release · 1966–2025

Brewer's Sparrow In Southern Rockies / Colorado Plateau

All regionsSouthern Rockies / Colorado PlateauArid-land birds

Brewer's Sparrow in Southern Rockies / Colorado Plateau has surged: up 114% on the route-weighted index since 1970.

+114%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 →
183Routes 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 surged in Southern Rockies / Colorado Plateau: up 114% 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 15% by 2030 — from 6.0 in 2025 to a central estimate of 6.9 (95% range 2.6–11). A 5-year backtest shows a typical error of ±28.9%, with 100% of held-out values landing inside the 95% band.

+15%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 →
6.9Projected 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 →
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 →
±28.9%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 Southern Rockies / Colorado Plateau is projected to rise about 15% by 2030 — from 6.0 in 2025 to a central estimate of 6.9 (95% range 2.6–11). A 5-year backtest shows a typical error of ±28.9%, 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 →
20266.72.511
20276.82.511
20286.82.611
20296.82.611
20306.92.611

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 →
Beck 2UTAH682025
DinosaurCOLORADO602025
WaldenCOLORADO592025
AltonahUTAH562025
Wray GulchCOLORADO532025
M Warner ResUTAH532025
Fish Lake NfUTAH452025
Black Sulphur CrCOLORADO402025
BeckUTAH401987
MonticelloUTAH362025
VernalUTAH352018
YampaCOLORADO342023
Lost Cr. ResUTAH342018
MoscaCOLORADO332025
Ant Flat-Ogden CanUTAH312025
PiedraCOLORADO301999
Baxter PassCOLORADO282024
AntonitoCOLORADO272004
Moon Lake 2UTAH272023
Uintah NfUTAH251994
FayetteUTAH242025
Piceance BasinCOLORADO222012
Skyline DrivUTAH222025
BlancaCOLORADO171987
DoylevilleCOLORADO172025

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