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

Fox Sparrow In Northern Rockies

All regionsNorthern RockiesForest birds

Fox Sparrow in Northern Rockies has risen sharply: up 58% on the route-weighted index since 1970.

+58%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 →
98Routes 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 →

Fox Sparrow has risen sharply in Northern Rockies: up 58% on the route-weighted index since 1970.

Fox Sparrow In Northern Rockies Population Forecast

If the recent trend holds, Fox Sparrow in Northern Rockies is projected to fall about 17% by 2030 — from 0.99 in 2025 to a central estimate of 0.82 (95% range 0.36–1.3). A 5-year backtest shows a typical error of ±18.1%, with 100% of held-out values landing inside the 95% band.

-17%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 →
0.82Projected 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 →
0.36–1.395% 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 →
±18.1%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, Fox Sparrow in Northern Rockies is projected to fall about 17% by 2030 — from 0.99 in 2025 to a central estimate of 0.82 (95% range 0.36–1.3). A 5-year backtest shows a typical error of ±18.1%, 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 →
20260.790.331.3
20270.800.341.3
20280.810.341.3
20290.810.351.3
20300.820.361.3

Routes In Northern Rockies

Routes recording Fox 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 →
Buckskin MtnWYOMING182025
Whitefish LakeMONTANA172024
Logan PassMONTANA142025
AlpineWYOMING142025
AveryIDAHO122025
WoodruffUTAH102025
Lolo PassIDAHO92019
Soda LakeWYOMING82025
PierceIDAHO72007
SunbeamIDAHO52025
WoodmanMONTANA52025
Hebgen LakeMONTANA52025
Colter BayWYOMING51999
WilsonWYOMING52025
CentervilleIDAHO42025
Fish CreekMONTANA42024
OttoWYOMING41987
Great DivideCOLORADO31977
ChallisIDAHO32025
Baldy MountainIDAHO32016
BurgdorfIDAHO32025
Sawtooth City 2IDAHO32025
ChestnutMONTANA32009
TroyOREGON32025
OchocoOREGON32021

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