BirdAnalyst
Species · New Hampshire · BBS 2026 Release · 1966–2025

Barn Swallow Population Trend in New Hampshire

All statesAerial insectivores

Barn Swallow in New Hampshire has collapsed: down 77% on the route-weighted index since 1968.

-77%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 →
26Routes 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 Barn 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 →

Barn Swallow has collapsed in New Hampshire: down 77% on the route-weighted index since 1968.

Barn Swallow Population Forecast in New Hampshire

If the recent trend holds, Barn Swallow in New Hampshire is projected to fall about 100% by 2030 — from 4.1 in 2025 to a central estimate of 0.00 (95% range 0.00–5.5). A 5-year backtest shows a typical error of ±128%, with 60% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–5.595% 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 →
±128%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, Barn Swallow in New Hampshire is projected to fall about 100% by 2030 — from 4.1 in 2025 to a central estimate of 0.00 (95% range 0.00–5.5). A 5-year backtest shows a typical error of ±128%, with 60% 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 →
20260.000.005.5
20270.000.005.5
20280.000.005.5
20290.000.005.5
20300.000.005.5

Barn Swallow Survey Routes in New Hampshire

Routes recording Barn 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 →
Crawford Not3119751966
Walpole1620251966
Glen1420251975
Fitzwilliam1120251966
Gilmantn I W920241969
Canterbury820251966
Mt Chocorua820251966
Hopkinton620251966
Wilmot520251966
Dixville Notch 2520252018
Milan420251966
Dover320251966
Marlow320251966
Franconia320251966
Dixvil Notch320171966
Brentwood219981966
Epsom220251966
Concord220251966
Lempster220251966
Stratford220211966
Jeffers Ntch220231996
Peterborough120251966
Strafford120251966
Jefferson Hl120221966
Clarksville120091966

Barn Swallow Population Trend in Other States

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

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