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

Northern Waterthrush Population Trend in Alaska

All statesForest birds

Northern Waterthrush in Alaska has surged: up 180% on the route-weighted index since 1975.

+180%Since 1975TrendPercent 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 →
104Routes 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 →
47YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Northern Waterthrush 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 →

Northern Waterthrush has surged in Alaska: up 180% on the route-weighted index since 1975.

Northern Waterthrush Population Forecast in Alaska

If the recent trend holds, Northern Waterthrush in Alaska is projected to fall about 18% by 2029 — from 11 in 2024 to a central estimate of 8.8 (95% range 0.03–18). A 5-year backtest shows a typical error of ±10.2%, with 100% of held-out values landing inside the 95% band.

-18%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 →
8.8Projected 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 →
0.03–1895% 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 →
±10.2%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, Northern Waterthrush in Alaska is projected to fall about 18% by 2029 — from 11 in 2024 to a central estimate of 8.8 (95% range 0.03–18). A 5-year backtest shows a typical error of ±10.2%, 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 →
20258.60.0017
20268.70.0017
20278.70.0018
20288.80.0018
20298.80.0318

Northern Waterthrush Survey Routes in Alaska

Routes recording Northern Waterthrush 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 →
Gweek River12920021994
Tupuknuk12619951995
Anvik River11120241998
Unalakleet River10720241996
Mud River7920241993
Hather Creek6220241994
Council4720241993
Goose Bay4619821975
Selawik (Short)4219871986
Dillingham (Short)3919841984
Nicholai Sl3820241993
Togiak River3620051999
Koyukuk Riv.3220011994
Salmon Lake3220241993
Galena (Short)2520241986
Kobuk River (Short)2419921991
Nome2120231993
Chena River2019881988
Kanuti Lake2020242006
Petersville1920241986
Bear Creek1819911986
Goodnews Bay1820051999
Kugarak (Short)1819871986
Thompson Pas1520242001
Ruby1520241995

Northern Waterthrush Population Trend in Other States

connecticutidahomainemarylandmassachusettsmichiganminnesotamontananew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiopennsylvaniarhode-islandvermontvirginiawashingtonwest-virginiawisconsinwyoming

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