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

Purple Martin Population Trend in Maine

All statesAerial insectivores

Purple Martin in Maine has fallen sharply: down 60% on the route-weighted index since 1973.

-60%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 →
22Routes 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 →
28YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Purple Martin 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 →

Purple Martin has fallen sharply in Maine: down 60% on the route-weighted index since 1973.

Purple Martin Population Forecast in Maine

If the recent trend holds, Purple Martin in Maine is projected to rise about 381% by 2015 — from 0.05 in 2010 to a central estimate of 0.26 (95% range 0.00–1.0). A 5-year backtest shows a typical error of ±619.3%, with 100% of held-out values landing inside the 95% band.

+381%Change by 2015TrendPercent 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 →
0.26Projected 2015 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.095% 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 →
±619.3%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, Purple Martin in Maine is projected to rise about 381% by 2015 — from 0.05 in 2010 to a central estimate of 0.26 (95% range 0.00–1.0). A 5-year backtest shows a typical error of ±619.3%, with 100% of held-out values landing inside the 95% band.19672015
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 →
20110.260.001.0
20120.260.001.0
20130.260.001.0
20140.260.001.0
20150.260.001.0

Purple Martin Survey Routes in Maine

Routes recording Purple Martin 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 →
Winn1219791978
Cambridge1019731973
Grnd Lk Strm920001990
Biddeford519761976
Otisfield Gr519891977
Washburn419911979
Newcastle219721972
Harmony220101985
Brooks219961996
Charleston219771977
Wytopitlock219821978
Medway219791979
Hudson219991978
Bethel119911991
Hartford119811981
Manchester119891979
East Troy119721972
Hermon119861967
Northfield119791977
Waite119771977
Ludlow119781978
St David119891989

Purple Martin Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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