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Species · Alaska · BBS 2026 Release · 1966–2025

American Tree Sparrow Population Trend in Alaska

All statesForest birds

American Tree Sparrow in Alaska has surged: up 500% on the route-weighted index since 1977.

+500%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 →
73Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
46YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable American Tree Sparrow Trends in AlaskaNotable 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 Alaska: up 500% on the route-weighted index since 1977.

American Tree Sparrow Population Forecast in Alaska

If the recent trend holds, American Tree Sparrow in Alaska is projected to rise about 15% by 2030 — from 6.9 in 2025 to a central estimate of 8.0 (95% range 1.2–15). A 5-year backtest shows a typical error of ±11.7%, with 100% of held-out values landing inside the 95% band.

+15%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 →
8.0Projected 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 →
1.2–1595% 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 →
±11.7%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, American Tree Sparrow in Alaska is projected to rise about 15% by 2030 — from 6.9 in 2025 to a central estimate of 8.0 (95% range 1.2–15). A 5-year backtest shows a typical error of ±11.7%, 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 →
20267.80.9915
20277.81.015
20287.91.115
20297.91.115
20308.01.215

American Tree Sparrow Survey Routes in Alaska

Routes recording American Tree Sparrow in Alaska.
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 →
Happy Valley13920251993
Toklat9420241982
Savage8220251986
Galbraith L.7720251995
Maclaren6020251982
Pinoche Tral (Short)4819841984
Gweek River3720021994
Nome3620231993
Togiak River2920051999
Red Dog2720251995
Kanektok Riv2420051995
Cantwell2220211982
Monahan2020211983
St. Mary'S1520141993
Kobuk River (Short)1319921991
Goodnews Bay1320051999
Dillingham1120121993
Circle1020181992
Salmon Lake1020191993
Porcupine R.1019941994
Kugarak (Short)919871986
Tupuknuk819951995
Chatanika R620151968
Paxson Lake619971991
Caribou Mtn.620251994

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