BirdAnalyst
Species · Alaska · BBS 2025 Release · 1966–2024

American Tree Sparrow Population Trend in Alaska

All statesGeneralists

American Tree Sparrow in Alaska has surged: up 518% on the route-weighted index since 1977.

+518%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 →
45YearsYears 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 518% 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 stay roughly flat through 2029, near 8.0 (95% range 1.2–15). A 5-year backtest shows a typical error of ±10.9%, with 100% of held-out values landing inside the 95% band.

+4%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 →
8.0Projected 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 →
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 →
±10.9%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 stay roughly flat through 2029, near 8.0 (95% range 1.2–15). A 5-year backtest shows a typical error of ±10.9%, 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 →
20257.80.9815
20267.91.015
20277.91.115
20288.01.115
20298.01.215

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 Valley14920241993
Savage11420241986
Toklat9420241982
Galbraith L.7420241995
Pinoche Tral (Short)4819841984
Maclaren4620241982
Gweek River3720021994
Nome3620231993
Togiak River2920051999
Kanektok Riv2420051995
Cantwell2220211982
Monahan2020211983
Red Dog1820241995
St. Mary'S1520141993
Kobuk River (Short)1319921991
Goodnews Bay1320051999
Dillingham1120121993
Circle1020181992
Salmon Lake1020191993
Porcupine R.1019941994
Kugarak (Short)919871986
Tupuknuk819951995
Chatanika R620151968
Paxson Lake619971991
Manley Ht Sp620221993

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