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Species · Massachusetts · BBS 2026 Release · 1966–2025

Northern Waterthrush Population Trend in Massachusetts

All statesForest birds

Northern Waterthrush in Massachusetts has surged: up 262% on the route-weighted index since 1970.

+262%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 →
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 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 262% 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 stay roughly flat through 2030, near 0.32 (95% range 0.12–0.52). A 5-year backtest shows a typical error of ±27%, with 100% of held-out values landing inside the 95% band.

+2%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 →
0.32Projected 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 →
0.12–0.5295% 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%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 stay roughly flat through 2030, near 0.32 (95% range 0.12–0.52). A 5-year backtest shows a typical error of ±27%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.300.100.50
20270.310.110.51
20280.310.110.51
20290.310.120.51
20300.320.120.52

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 →
Marion220252018
Chesterfield220241973
Ware River120211993
Prattville120181969
Brockton120152015
Littleton120141969
N Oxford120242021
Mansfield120191974
Belchertown120241979
S Barre119851968
N Orange120251970
Cummington120091973
Pittsfield120061969
Sheffield120081980
Monterey120252019
Holden120101986
Warren 2120222018
Cummington 2120252018
Hancock120152009

Northern Waterthrush Population Trend in Other States

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

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