BirdAnalyst
Species · BCR 4 · BBS 2026 Release · 1966–2025

Fox Sparrow In BCR 4

All regionsBCR 4Forest birds

Fox Sparrow in BCR 4 has declined: down 41% on the route-weighted index since 1976.

-41%Since 1976TrendPercent 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 →
66Routes 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 →
47YearsYears 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 →

No notable trend signals for Fox Sparrow in BCR 4. See the full index history below.

Fox Sparrow In BCR 4 Population Forecast

If the recent trend holds, Fox Sparrow in BCR 4 is projected to rise about 77% by 2030 — from 9.2 in 2025 to a central estimate of 16 (95% range 7.0–26). A 5-year backtest shows a typical error of ±78.2%, with 60% of held-out values landing inside the 95% band.

+77%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 →
16Projected 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 →
7.0–2695% 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 →
±78.2%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 BCR 4 is projected to rise about 77% by 2030 — from 9.2 in 2025 to a central estimate of 16 (95% range 7.0–26). A 5-year backtest shows a typical error of ±78.2%, with 60% 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 →
2026166.525
2027166.625
2028166.725
2029166.825
2030167.026

Routes In BCR 4

Routes recording Fox Sparrow in BCR 4.
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 →
Goose BayALASKA481982
Anvik RiverALASKA462024
KachemakALASKA362025
Anchor RiverALASKA352025
ToklatALASKA342024
CohoeALASKA332023
Koyukuk Riv.ALASKA322001
Mt. FairplayALASKA282025
DeltaALASKA282024
Mud RiverALASKA272024
Caribou Mtn.ALASKA262025
TatalinaALASKA232019
ColdfootALASKA222025
Hather CreekALASKA222024
Unalakleet RiverALASKA202024
RubyALASKA192025
Kobuk River (Short)ALASKA191992
SavageALASKA182025
EagleALASKA162025
Seven LakesALASKA162025
HomerALASKA141982
Chatanika RALASKA132025
CantwellALASKA132025
ChickenALASKA122025
Lake LouiseALASKA112025

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