BirdAnalyst
Species · Maine · BBS 2026 Release · 1966–2025

Swamp Sparrow Population Trend in Maine

All statesWetland birds

Swamp Sparrow in Maine has risen sharply: up 51% on the route-weighted index since 1968.

+51%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 →
68Routes 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 →
59YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Swamp Sparrow 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 →

Swamp Sparrow has risen sharply in Maine: up 51% on the route-weighted index since 1968.

Swamp Sparrow Population Forecast in Maine

If the recent trend holds, Swamp Sparrow in Maine is projected to fall about 13% by 2030 — from 1.1 in 2025 to a central estimate of 0.92 (95% range 0.45–1.4). A 5-year backtest shows a typical error of ±25.2%, with 100% of held-out values landing inside the 95% band.

-13%Change by 2030TrendPercent 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 →
0.92Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.45–1.495% 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 →
±25.2%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, Swamp Sparrow in Maine is projected to fall about 13% by 2030 — from 1.1 in 2025 to a central estimate of 0.92 (95% range 0.45–1.4). A 5-year backtest shows a typical error of ±25.2%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20260.910.441.4
20270.920.451.4
20280.920.451.4
20290.920.451.4
20300.920.451.4

Swamp Sparrow Survey Routes in Maine

Routes recording Swamp Sparrow 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 →
Northfield819811976
Forest Sta620001970
Waite519771977
Turner420021972
Greenwood420251974
Benton419711971
Grnd Lk Strm420001966
Cape Neddick319731972
Bethel320191977
Reeds320251992
East Troy320211972
Brooks320211979
Pillsbury Pd319681968
Washburn320051995
Northfield 2320221992
Jefferson320101991
Westbrook220241977
Andover220212010
Moose River220081983
Carrying Pl220251980
Charleston220211977
Wytopitlock220251978
Medway220251976
Clayton Lake220001977
Priestly Br.220091998

Swamp Sparrow Population Trend in Other States

connecticutdelawareillinoisindianaiowamarylandmassachusettsmichiganminnesotanebraskanew-hampshirenew-jerseynew-yorknorth-dakotaohiopennsylvaniarhode-islandsouth-dakotavermontvirginiawest-virginiawisconsin

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.