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

Pine Warbler Population Trend in Maine

All statesForest birds

Pine Warbler in Maine has surged: up 80× on the route-weighted index since 1973.

80×Since 1973TrendPercent 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 →
51YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Pine 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 increasecomputed 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 →

Pine Warbler has surged in Maine: up 80× on the route-weighted index since 1973.

Pine Warbler Population Forecast in Maine

If the recent trend holds, Pine Warbler in Maine is projected to fall about 28% by 2029 — from 6.7 in 2024 to a central estimate of 4.8 (95% range 3.2–6.4). A 5-year backtest shows a typical error of ±44.4%, with 0% of held-out values landing inside the 95% band.

-28%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 →
4.8Projected 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 →
3.2–6.495% 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, Pine Warbler in Maine is projected to fall about 28% by 2029 — from 6.7 in 2024 to a central estimate of 4.8 (95% range 3.2–6.4). A 5-year backtest shows a typical error of ±44.4%, with 0% of held-out values landing inside the 95% band.19712029
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 →
20254.52.96.1
20264.63.06.2
20274.73.16.3
20284.73.16.3
20294.83.26.4

Pine Warbler Survey Routes in Maine

Routes recording Pine 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 →
Brooks2020191986
Charleston1520192005
Winn1520221997
Turner1420101973
Reeds1320241993
Aurora1320211982
Carrying Pl1320242002
Greenwood1120242014
Medway1120181976
Turner 21120242011
Bowdoin Ctr1020211972
Cornville1020242012
Westbrook920241979
East Troy920191976
Brownfield 2920242010
Brownfield820092009
Hartford720241983
Eastbrook720241977
Cooper720212005
Rome720241996
Cape Neddick620241978
Carrabassett620241988
Newcastle520241978
Harmony520241989
Hermon520192009

Pine Warbler Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianakentuckylouisianamarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsin

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