BirdAnalyst
Species · Maine · BBS 2025 Release · 1966–2024

Cape May Warbler Population Trend in Maine

All statesForest birds

Cape May Warbler in Maine has fallen sharply: down 74% on the route-weighted index since 1974.

-74%Since 1974TrendPercent 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 →
57Routes 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 →
49YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cape May 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 →

Cape May Warbler has fallen sharply in Maine: down 74% on the route-weighted index since 1974.

Cape May Warbler Population Forecast in Maine

If the recent trend holds, Cape May Warbler in Maine is projected to fall about 100% by 2027 — from 0.29 in 2022 to a central estimate of 0.00 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±79.8%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2027TrendPercent 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 2027 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.6195% 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 →
±79.8%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, Cape May Warbler in Maine is projected to fall about 100% by 2027 — from 0.29 in 2022 to a central estimate of 0.00 (95% range 0.00–0.61). A 5-year backtest shows a typical error of ±79.8%, with 100% of held-out values landing inside the 95% band.19682027
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 →
20230.040.000.66
20240.030.000.65
20250.020.000.63
20260.000.000.62
20270.000.000.61

Cape May Warbler Survey Routes in Maine

Routes recording Cape May 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 Pd819681968
Baxter619841977
Northfield419811976
Clayton Lake420081977
Otisfield Gr319751975
Seboomook Lk320061974
Greenville320221976
Benedicta320221980
Grnd Lk Strm319931990
Baker Lake320091994
Heron Lake320031984
Freedom220062006
Eastbrook219811973
Aurora219941976
Carrying Pl220051980
Winn219981978
Ludlow219981968
Horse Mtn219941984
Cornville220192019
Telos219951995
Clayton Lake 2220132010
Rome220011999
Northfield 2119961992
Newcastle119931993
Wilson Mills119871984

Cape May Warbler Population Trend in Other States

michiganminnesotanew-hampshirenew-yorkvermontwisconsin

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