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Species · Maine · BBS 2025 Release · 1966–2024

Canada Warbler Population Trend in Maine

All statesForest birds

Canada Warbler in Maine 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 →
73Routes 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 Canada Warbler 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 →

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

Canada Warbler Population Forecast in Maine

If the recent trend holds, Canada Warbler in Maine is projected to fall about 44% by 2029 — from 0.37 in 2024 to a central estimate of 0.21 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±29.1%, with 100% of held-out values landing inside the 95% band.

-44%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 →
0.21Projected 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 →
0.00–1.895% 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 →
±29.1%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 Maine is projected to fall about 44% by 2029 — from 0.37 in 2024 to a central estimate of 0.21 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±29.1%, 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 →
20250.320.001.9
20260.290.001.9
20270.260.001.8
20280.230.001.8
20290.210.001.8

Canada Warbler Survey Routes in Maine

Routes recording Canada Warbler 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 →
Pillsbury Pd2519681968
Northfield619811976
Topsfield619921979
Wilson Mills420241983
Turner320021973
Carrying Pl320221979
Baxter319881977
Seboomook Lk320141978
Forest Sta320001966
Clayton Lake320011977
Ludlow319981968
St David320051982
Newcastle220031972
Bethel220211977
Greenwood219851973
Warren219901979
Eastbrook219961972
Castine220021976
Charleston220141987
Medway220181976
Hudson220161977
Ashland220081980
Ft Fairfield220051997
Weeks Brook220161997
Baker Lake220082008

Canada Warbler Population Trend in Other States

connecticutgeorgiaindianamarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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