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Species · Maine · BBS 2025 Release · 1966–2024

Swainson's Thrush Population Trend in Maine

All statesForest birds

Swainson's Thrush in Maine has fallen sharply: down 52% on the route-weighted index since 1968.

-52%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 →
63Routes 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 Swainson's Thrush 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 →

Swainson's Thrush has fallen sharply in Maine: down 52% on the route-weighted index since 1968.

Swainson's Thrush Population Forecast in Maine

If the recent trend holds, Swainson's Thrush in Maine is projected to rise about 91% by 2029 — from 2.0 in 2024 to a central estimate of 3.8 (95% range 1.1–6.5). A 5-year backtest shows a typical error of ±82.7%, with 100% of held-out values landing inside the 95% band.

+91%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 →
3.8Projected 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 →
1.1–6.595% 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 →
±82.7%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, Swainson's Thrush in Maine is projected to rise about 91% by 2029 — from 2.0 in 2024 to a central estimate of 3.8 (95% range 1.1–6.5). A 5-year backtest shows a typical error of ±82.7%, 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 →
20253.81.06.5
20263.81.16.5
20273.81.16.5
20283.81.16.5
20293.81.16.5

Swainson's Thrush Survey Routes in Maine

Routes recording Swainson's Thrush 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 →
Nesowadnehun3320211990
Waite3219771977
Pillsbury Pd2319681968
Baker Lake2220091994
Wilson Mills2120241983
Clayton Lake 21920132010
Weeks Brook1820161995
Heron Lake1820031983
Carrying Pl1620241979
Priestly Br.1420131994
Yankeetuladi1320091994
Big Twenty1220081993
Seboomook Lk1120141974
Baker Lake 21020132010
Northfield919811976
St David920051982
Forest Sta820001966
Clayton Lake720081977
Ludlow719981968
Big Twenty 2720092009
Horse Mtn620111983
Lake Moxie620222006
Moose River420081983
Andover320212010
Brooks320161977

Swainson's Thrush Population Trend in Other States

alaskaarizonacaliforniacoloradoconnecticutidahoillinoismarylandmassachusettsmichiganminnesotamontananebraskanevadanew-hampshirenew-mexiconew-yorknorth-carolinaoregonpennsylvaniasouth-dakotautahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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