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

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 →
58YearsYears 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 2029 — from 5.5 in 2024 to a central estimate of 0.00 (95% range 0.00–5.4). A 5-year backtest shows a typical error of ±126.4%, with 60% of held-out values landing inside the 95% band.

-100%Change 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 →
0.00Projected 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 →
0.00–5.495% 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 →
±126.4%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, Barn Swallow in New Hampshire is projected to fall about 100% by 2029 — from 5.5 in 2024 to a central estimate of 0.00 (95% range 0.00–5.4). A 5-year backtest shows a typical error of ±126.4%, with 60% 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 →
20250.000.005.4
20260.000.005.4
20270.000.005.4
20280.000.005.4
20290.000.005.4

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
Fitzwilliam2120241966
Walpole2020241966
Canterbury1720241966
Peterborough1220241966
Gilmantn I W920241969
Glen920241975
Dover620241966
Dixville Notch 2520242018
Concord420241966
Marlow420241966
Milan420241966
Lempster320241966
Dixvil Notch320171966
Brentwood219981966
Strafford220241966
Stratford220211966
Jeffers Ntch220231996
Hopkinton120241966
Epsom120231966
Wilmot120241966
Mt Chocorua120241966
Jefferson Hl120221966
Franconia120241966
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 2026-05-22.