BirdAnalyst
Species · BCR 10 · BBS 2026 Release · 1966–2025

Brewer's Sparrow In Northern Rockies

All regionsNorthern RockiesArid-land birds

Brewer's Sparrow in Northern Rockies has surged: up 145% on the route-weighted index since 1970.

+145%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 →
171Routes 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 Northern Rockies: up 145% on the route-weighted index since 1970.

Brewer's Sparrow In Northern Rockies Population Forecast

If the recent trend holds, Brewer's Sparrow in Northern Rockies is projected to fall about 13% by 2030 — from 15 in 2025 to a central estimate of 13 (95% range 6.7–20). A 5-year backtest shows a typical error of ±20%, with 100% of held-out values landing inside the 95% band.

-13%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 →
13Projected 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 →
6.7–2095% 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 →
±20%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 Northern Rockies is projected to fall about 13% by 2030 — from 15 in 2025 to a central estimate of 13 (95% range 6.7–20). A 5-year backtest shows a typical error of ±20%, 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 →
2026136.620
2027136.620
2028136.620
2029136.720
2030136.720

Routes In Northern Rockies

Routes recording Brewer's Sparrow in Northern Rockies.
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 →
Seedskadee 2WYOMING1262024
RyegrassWYOMING1222025
Neponset ResUTAH1082018
MckinnonWYOMING861986
Great DivideCOLORADO822025
MaybellCOLORADO762025
Clover CreekOREGON752025
RelianceWYOMING742025
Saleratus CrUTAH722018
LamontWYOMING702025
BeaverheadMONTANA672025
MeeteetseWYOMING652025
Bear CreekWYOMING642025
Patrick DrawWYOMING631980
Elk Horn 2WYOMING632025
Flamin GorgeWYOMING632025
BairoilWYOMING622025
LayCOLORADO612025
Big SandyWYOMING612025
DiamondvilleWYOMING601982
Red RockMONTANA532025
NowoodWYOMING532025
Sawtooth CtyIDAHO522014
Crawford MtsUTAH512023
MoranWYOMING512016

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