BirdAnalyst
Species · BCR 2 · BBS 2025 Release · 1966–2024

Song Sparrow In BCR 2

All regionsBCR 2Generalists

Song Sparrow in BCR 2 has fallen sharply: down 71% on the route-weighted index since 1985.

-71%Since 1985TrendPercent 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 →
10Routes 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 →
32YearsYears 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 fallen sharply in BCR 2: down 71% on the route-weighted index since 1985.

Forecast

If the recent trend holds, Song Sparrow in BCR 2 is projected to rise about 422% by 2029 — from 0.11 in 2024 to a central estimate of 0.58 (95% range 0.00–1.5). A 5-year backtest shows a typical error of ±325.5%, with 100% of held-out values landing inside the 95% band.

+422%Change by 2029TrendPercent 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 →
0.58Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.595% 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 →
±325.5%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 2 is projected to rise about 422% by 2029 — from 0.11 in 2024 to a central estimate of 0.58 (95% range 0.00–1.5). A 5-year backtest shows a typical error of ±325.5%, with 100% of held-out values landing inside the 95% band.19832029
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 →
20250.560.001.5
20260.560.001.5
20270.570.001.5
20280.570.001.5
20290.580.001.5

Routes In BCR 2

Routes recording Song Sparrow in BCR 2.
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 →
Togiak RiverALASKA51994
Kanektok RivALASKA51999
Cold BayALASKA22000
KodiakALASKA11983
Katmai N.P.ALASKA11997
ChiniakALASKA12023
Kodiak 2ALASKA12024
Salmon LakeALASKA12010
Goodnews BayALASKA11999
Cold Bay (Short)ALASKA11991

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