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Species · Connecticut · BBS 2025 Release · 1966–2024

Northern Waterthrush Population Trend in Connecticut

All statesForest birds

Northern Waterthrush in Connecticut has fallen sharply: down 54% on the route-weighted index since 1969.

-54%Since 1969TrendPercent 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 →
16Routes 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 →
50YearsYears 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 ConnecticutNotable 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 Connecticut: down 54% on the route-weighted index since 1969.

Northern Waterthrush Population Forecast in Connecticut

If the recent trend holds, Northern Waterthrush in Connecticut is projected to fall about 19% by 2029 — from 0.22 in 2024 to a central estimate of 0.18 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±44.4%, with 100% of held-out values landing inside the 95% band.

-19%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 →
0.18Projected 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 →
0.00–0.4695% 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 →
±44.4%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 Connecticut is projected to fall about 19% by 2029 — from 0.22 in 2024 to a central estimate of 0.18 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±44.4%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.190.000.47
20260.180.000.46
20270.180.000.46
20280.180.000.46
20290.180.000.46

Northern Waterthrush Survey Routes in Connecticut

Routes recording Northern Waterthrush in Connecticut.
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 →
E Hartland219711968
New Hartford220111998
No Woodbury219981973
Woodstock 2220242018
New Hartford219791978
Mystic120021978
Uncasville120231999
Woodstock120051968
Willimantic120181967
Sherman119801980
Danbury120152009
Warren120081972
Long Hill120181982
Mid Haddam120231975
Southington119851976
Granby120232014

Northern Waterthrush Population Trend in Other States

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

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