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Species · Maine · BBS 2025 Release · 1966–2024

Northern Waterthrush Population Trend in Maine

All statesForest birds

Northern Waterthrush in Maine has fallen sharply: down 64% on the route-weighted index since 1968.

-64%Since 1968TrendPercent 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 →
72Routes 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 →
58YearsYears 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 MaineNotable 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 declinecomputed 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 fallen sharply in Maine: down 64% on the route-weighted index since 1968.

Northern Waterthrush Population Forecast in Maine

If the recent trend holds, Northern Waterthrush in Maine is projected to rise about 109% by 2029 — from 0.42 in 2024 to a central estimate of 0.88 (95% range 0.11–1.6). A 5-year backtest shows a typical error of ±85.9%, with 100% of held-out values landing inside the 95% band.

+109%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 →
0.88Projected 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 →
0.11–1.695% 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 →
±85.9%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 Maine is projected to rise about 109% by 2029 — from 0.42 in 2024 to a central estimate of 0.88 (95% range 0.11–1.6). A 5-year backtest shows a typical error of ±85.9%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.930.161.7
20260.920.151.7
20270.900.141.7
20280.890.131.7
20290.880.111.6

Northern Waterthrush Survey Routes in Maine

Routes recording Northern Waterthrush in Maine.
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 →
St David720051982
Washburn620051979
Pillsbury Pd519681968
Deblois419871987
Telos420061995
Big Twenty 2420092009
Heron Lake420031983
Andover320212010
East Troy320171976
Medway320181976
Clayton Lake320081977
Ludlow319981968
Horse Mtn320111983
Big Twenty320081995
Weeks Brook320161995
Yankeetuladi320091994
Northfield 2220211992
Wilson Mills220241987
Greenwood220192019
Warren219901973
Harmony220241967
Brooks220141977
Hermon220191967
Northfield219811976
Moose River220081983

Northern Waterthrush Population Trend in Other States

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

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