BirdAnalyst
Species · BCR 4 · BBS 2025 Release · 1966–2024

Song Sparrow In BCR 4

All regionsBCR 4Generalists

Song Sparrow in BCR 4 has collapsed: down 98% on the route-weighted index since 1982.

-98%Since 1982TrendPercent 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 →
18Routes 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 →
35YearsYears 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 declinecomputed 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 →

Song Sparrow has collapsed in BCR 4: down 98% on the route-weighted index since 1982.

Forecast

If the recent trend holds, Song Sparrow in BCR 4 is projected to fall about 100% by 2028 — from 0.08 in 2023 to a central estimate of 0.00 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±2236.7%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2028TrendPercent 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 →
0.00Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.795% 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 →
±2236.7%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, Song Sparrow in BCR 4 is projected to fall about 100% by 2028 — from 0.08 in 2023 to a central estimate of 0.00 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±2236.7%, with 100% of held-out values landing inside the 95% band.19772028
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 →
20240.000.001.7
20250.000.001.7
20260.000.001.7
20270.000.001.7
20280.000.001.7

Routes In BCR 4

Routes recording Song 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 →
SourdoughALASKA32013
Ft. RichrdsnALASKA31996
Mccarthy Rd2ALASKA31995
HomerALASKA21982
KalifonskyALASKA22023
ChistochinaALASKA11999
ToklatALASKA11999
Skilak LakeALASKA11985
Hatcher PassALASKA12008
Swan Lake RdALASKA12001
Anchor RiverALASKA12023
Seven LakesALASKA12010
KachemakALASKA12021
Burma RoadALASKA12002
Hather CreekALASKA12009
McgrathALASKA11998
Paxson LakeALASKA11997
Nabesna RoadALASKA11996

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