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Species · Massachusetts · BBS 2025 Release · 1966–2024

Northern Waterthrush Population Trend in Massachusetts

All statesForest birds

Northern Waterthrush in Massachusetts has surged: up 256% on the route-weighted index since 1970.

+256%Since 1970TrendPercent 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 →
19Routes 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 →
52YearsYears 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 MassachusettsNotable 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 Massachusetts: up 255% on the route-weighted index since 1970.

Northern Waterthrush Population Forecast in Massachusetts

If the recent trend holds, Northern Waterthrush in Massachusetts is projected to fall about 33% by 2029 — from 0.47 in 2024 to a central estimate of 0.31 (95% range 0.11–0.51). A 5-year backtest shows a typical error of ±41.4%, with 100% of held-out values landing inside the 95% band.

-33%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 →
0.31Projected 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 →
0.11–0.5195% 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 →
±41.4%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 Massachusetts is projected to fall about 33% by 2029 — from 0.47 in 2024 to a central estimate of 0.31 (95% range 0.11–0.51). A 5-year backtest shows a typical error of ±41.4%, 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 →
20250.300.100.50
20260.300.100.50
20270.300.100.51
20280.310.110.51
20290.310.110.51

Northern Waterthrush Survey Routes in Massachusetts

Routes recording Northern Waterthrush in Massachusetts.
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 →
Chesterfield220241973
Monterey220242019
Marion120232018
Ware River120211993
Prattville120181969
Brockton120152015
Littleton120141969
N Oxford120242021
Mansfield120191974
Belchertown120241979
S Barre119851968
N Orange120241970
Cummington120091973
Pittsfield120061969
Sheffield120081980
Holden120101986
Warren 2120222018
Cummington 2120232018
Hancock120152009

Northern Waterthrush Population Trend in Other States

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

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