BirdAnalyst
Species · Idaho · BBS 2026 Release · 1966–2025

Northern Waterthrush Population Trend in Idaho

All statesForest birds

Northern Waterthrush in Idaho has declined: down 48% on the route-weighted index since 1983.

-48%Since 1983TrendPercent 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 →
13Routes 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 →
31YearsYears 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 IdahoNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Northern Waterthrush in Idaho. See the full index history below.

Northern Waterthrush Population Forecast in Idaho

If the recent trend holds, Northern Waterthrush in Idaho is projected to stay roughly flat through 2030, near 0.12 (95% range 0.00–0.26). A 5-year backtest shows a typical error of ±179.5%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.12Projected 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 →
0.00–0.2695% 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 →
±179.5%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, Northern Waterthrush in Idaho is projected to stay roughly flat through 2030, near 0.12 (95% range 0.00–0.26). A 5-year backtest shows a typical error of ±179.5%, with 80% of held-out values landing inside the 95% band.19812030
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 →
20260.120.000.26
20270.120.000.26
20280.120.000.26
20290.120.000.26
20300.120.000.26

Northern Waterthrush Survey Routes in Idaho

Routes recording Northern Waterthrush in Idaho.
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 →
Lolo Pass320192000
Golden320102007
Pierce220072003
Naples120242002
Mivoden120251982
Avery120191981
Nezperce120122006
Marble Creek120191990
N Fork Cda R120162009
Rochat Divde120242003
Yellow Pine119981998
Sunbeam120182018
Coolin120221987

Northern Waterthrush Population Trend in Other States

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

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