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Species · Montana · BBS 2026 Release · 1966–2025

Northern Waterthrush Population Trend in Montana

All statesForest birds

Northern Waterthrush in Montana has surged: up 502% on the route-weighted index since 1973.

+502%Since 1973TrendPercent 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 →
43Routes 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 →
54YearsYears 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 MontanaNotable 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 Montana: up 502% on the route-weighted index since 1973.

Northern Waterthrush Population Forecast in Montana

If the recent trend holds, Northern Waterthrush in Montana is projected to rise about 77% by 2030 — from 0.61 in 2025 to a central estimate of 1.1 (95% range 0.46–1.7). A 5-year backtest shows a typical error of ±46.5%, with 100% of held-out values landing inside the 95% band.

+77%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 →
1.1Projected 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 →
0.46–1.795% 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 →
±46.5%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 Montana is projected to rise about 77% by 2030 — from 0.61 in 2025 to a central estimate of 1.1 (95% range 0.46–1.7). A 5-year backtest shows a typical error of ±46.5%, with 100% of held-out values landing inside the 95% band.19702030
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 →
20261.10.431.7
20271.10.441.7
20281.10.451.7
20291.10.461.7
20301.10.461.7

Northern Waterthrush Survey Routes in Montana

Routes recording Northern Waterthrush in Montana.
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 →
Inside Road1120251990
East Glacier Park1020252015
Sula720241977
Libby Dam620251979
Elliston520251972
Whitefish Lake520242018
Ninemile320251995
Wise River320251998
St. Mary 2320252009
St Mary220081977
Logan Pass220251980
Threemile Wa219931993
Arlee220241972
Woodman220251976
Chestnut220251983
Swan Lake220252017
Thompson Riv220222014
Pagil Gulch220212015
Clyde Park220222018
Painted Rock220221993
Kalispell120231970
Victor120061997
Cramer Creek120082008
Glen120101977
Willow Creek 2120162013

Northern Waterthrush Population Trend in Other States

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

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