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Species · Montana · BBS 2025 Release · 1966–2024

Northern Waterthrush Population Trend in Montana

All statesForest birds

Northern Waterthrush in Montana has surged: up 592% on the route-weighted index since 1973.

+592%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 →
53YearsYears 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 591% 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 36% by 2029 — from 0.82 in 2024 to a central estimate of 1.1 (95% range 0.50–1.7). A 5-year backtest shows a typical error of ±27.6%, with 100% of held-out values landing inside the 95% band.

+36%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 →
1.1Projected 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 →
0.50–1.795% 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 →
±27.6%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 36% by 2029 — from 0.82 in 2024 to a central estimate of 1.1 (95% range 0.50–1.7). A 5-year backtest shows a typical error of ±27.6%, with 100% of held-out values landing inside the 95% band.19702029
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 →
20251.10.461.7
20261.10.471.7
20271.10.481.7
20281.10.491.7
20291.10.501.7

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 →
East Glacier Park1820242015
Sula720241977
Logan Pass620241980
Elliston620241972
St. Mary 2620242009
Whitefish Lake520242018
Wise River520241998
Inside Road420241990
Swan Lake420242017
Ninemile320241995
Libby Dam220241979
St Mary220081977
Threemile Wa219931993
Arlee220241972
Augusta220221978
Thompson Riv220222014
Pagil Gulch220212015
Clyde Park220222018
Painted Rock220221993
Kalispell120231970
Victor120061997
Cramer Creek120082008
Glen120101977
Willow Creek 2120162013
Greenough120042002

Northern Waterthrush Population Trend in Other States

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

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