BirdAnalyst
Species · New Hampshire · BBS 2025 Release · 1966–2024

Northern Rough-winged Swallow Population Trend in New Hampshire

All statesAerial insectivores

Northern Rough-winged Swallow in New Hampshire has collapsed: down 76% on the route-weighted index since 1968.

-76%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 →
21Routes 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 →
57YearsYears 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 New HampshireNotable 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 New Hampshire: down 76% on the route-weighted index since 1968.

Northern Rough-winged Swallow Population Forecast in New Hampshire

If the recent trend holds, Northern Rough-winged Swallow in New Hampshire is projected to stay roughly flat through 2029, near 0.15 (95% range 0.00–0.48). A 5-year backtest shows a typical error of ±255.7%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.15Projected 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 →
0.00–0.4895% 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 →
±255.7%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, Northern Rough-winged Swallow in New Hampshire is projected to stay roughly flat through 2029, near 0.15 (95% range 0.00–0.48). A 5-year backtest shows a typical error of ±255.7%, 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 →
20250.160.000.49
20260.160.000.49
20270.160.000.49
20280.160.000.48
20290.150.000.48

Northern Rough-winged Swallow Survey Routes in New Hampshire

Routes recording Northern Rough-winged Swallow in New Hampshire.
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 →
Glen820101976
Clarksville720151975
Stratford320181974
Brentwood219721972
Mt Chocorua220041974
Lempster219851976
Dixvil Notch219751975
Peterborough120231994
Fitzwilliam120191968
Dover120241967
Hopkinton120121986
Concord120191966
Strafford120181975
Canterbury119851966
Gilmantn I W120141976
Wilmot119841973
Walpole120101968
Marlow120221968
Jefferson Hl120111985
Franconia120081969
Milan120101976

Northern Rough-winged Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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