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

Northern Rough-winged Swallow Population Trend in Maine

All statesAerial insectivores

Northern Rough-winged Swallow in Maine has collapsed: down 92% on the route-weighted index since 1972.

-92%Since 1972TrendPercent 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 →
27Routes 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 →
38YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Northern Rough-winged Swallow 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 →

Northern Rough-winged Swallow has collapsed in Maine: down 92% on the route-weighted index since 1972.

Northern Rough-winged Swallow Population Forecast in Maine

If the recent trend holds, Northern Rough-winged Swallow in Maine is projected to stay roughly flat through 2027, near 0.00 (95% range 0.00–0.29). A 5-year backtest shows a typical error of ±208.4%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.00–0.2995% 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 →
±208.4%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, Northern Rough-winged Swallow in Maine is projected to stay roughly flat through 2027, near 0.00 (95% range 0.00–0.29). A 5-year backtest shows a typical error of ±208.4%, with 100% of held-out values landing inside the 95% band.19672027
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 →
20230.000.000.29
20240.000.000.29
20250.000.000.29
20260.000.000.29
20270.000.000.29

Northern Rough-winged Swallow Survey Routes in Maine

Routes recording Northern Rough-winged Swallow 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 →
Benton1719721971
Moose River419941994
Bethel220062006
East Troy219931982
Hermon219871982
Hudson219891983
Church Hill220132013
Northfield 2120222022
Westbrook120072007
Biddeford119831976
Newcastle119861986
Turner119911989
Reeds120091996
Otisfield Gr120121978
Hartford120211999
Bowdoin Ctr120052005
Manchester119891989
Warren119741974
Freedom120041975
Harmony120161967
Hancock119931974
Castine119861986
Aurora120162005
Cooper120101975
Cambridge120082008

Northern Rough-winged Swallow Population Trend in Other States

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

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