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Species · Connecticut · BBS 2025 Release · 1966–2024

Canada Warbler Population Trend in Connecticut

All statesForest birds

Canada Warbler in Connecticut has collapsed: down 85% on the route-weighted index since 1968.

-85%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 →
14Routes 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 →
48YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Canada Warbler 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 →

Canada Warbler has collapsed in Connecticut: down 85% on the route-weighted index since 1968.

Canada Warbler Population Forecast in Connecticut

If the recent trend holds, Canada Warbler in Connecticut is projected to fall about 100% by 2028 — from 0.09 in 2023 to a central estimate of 0.00 (95% range 0.00–0.52). A 5-year backtest shows a typical error of ±103.1%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2028TrendPercent 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 →
0.00Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.5295% 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 →
±103.1%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, Canada Warbler in Connecticut is projected to fall about 100% by 2028 — from 0.09 in 2023 to a central estimate of 0.00 (95% range 0.00–0.52). A 5-year backtest shows a typical error of ±103.1%, with 100% of held-out values landing inside the 95% band.19662028
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 →
20240.000.000.52
20250.000.000.52
20260.000.000.52
20270.000.000.52
20280.000.000.52

Canada Warbler Survey Routes in Connecticut

Routes recording Canada Warbler 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 →
Warren420111972
Buckingham319721972
Mystic119831982
E Hartland119901966
Uncasville119771977
Woodstock120041968
Willimantic120001968
No Woodbury119851967
Sherman120081978
Danbury119721971
Long Hill119821974
Mid Haddam120142014
New Hartford119791972
Granby120231988

Canada Warbler Population Trend in Other States

georgiaindianamainemarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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