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

American Tree Sparrow In BCR 4

All regionsBCR 4Generalists

American Tree Sparrow in BCR 4 has surged: up 227% on the route-weighted index since 1977.

+227%Since 1977TrendPercent 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 →
44Routes 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 →
44YearsYears 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 →

American Tree Sparrow has surged in BCR 4: up 227% on the route-weighted index since 1977.

American Tree Sparrow In BCR 4 Population Forecast

If the recent trend holds, American Tree Sparrow in BCR 4 is projected to fall about 23% by 2029 — from 7.3 in 2024 to a central estimate of 5.6 (95% range 0.00–15). A 5-year backtest shows a typical error of ±34.6%, with 100% of held-out values landing inside the 95% band.

-23%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 →
5.6Projected 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 →
0.00–1595% 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 →
±34.6%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, American Tree Sparrow in BCR 4 is projected to fall about 23% by 2029 — from 7.3 in 2024 to a central estimate of 5.6 (95% range 0.00–15). A 5-year backtest shows a typical error of ±34.6%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20255.80.0015
20265.80.0015
20275.70.0015
20285.70.0015
20295.60.0015

Routes In BCR 4

Routes recording American Tree 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 →
SavageALASKA1142024
ToklatALASKA942024
Pinoche Tral (Short)ALASKA481984
MaclarenALASKA462024
CantwellALASKA222021
MonahanALASKA202021
Kobuk River (Short)ALASKA131992
CircleALASKA102018
Porcupine R.ALASKA101994
Chatanika RALASKA62015
Manley Ht SpALASKA62022
Paxson LakeALASKA61997
NebesnaALASKA51975
Donelly DomeALASKA52017
TatalinaALASKA52010
EagleALASKA42024
ChistochinaALASKA42023
Tangle LakesALASKA41987
WillowALASKA31996
Moose CreekALASKA32021
Kanuti LakeALASKA32022
SlanaALASKA22008
KalifonskyALASKA21982
Hatcher PassALASKA22011
Lake LouiseALASKA22011

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