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

Chimney Swift Population Trend in New Hampshire

All statesAerial insectivores

Chimney Swift in New Hampshire has fallen sharply: down 62% on the route-weighted index since 1968.

-62%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 →
25Routes 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 Chimney Swift 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 →

Chimney Swift has fallen sharply in New Hampshire: down 62% on the route-weighted index since 1968.

Chimney Swift Population Forecast in New Hampshire

If the recent trend holds, Chimney Swift in New Hampshire is projected to fall about 45% by 2029 — from 4.4 in 2024 to a central estimate of 2.4 (95% range 0.00–5.6). A 5-year backtest shows a typical error of ±27.2%, with 100% of held-out values landing inside the 95% band.

-45%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 →
2.4Projected 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 →
0.00–5.695% 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 →
±27.2%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, Chimney Swift in New Hampshire is projected to fall about 45% by 2029 — from 4.4 in 2024 to a central estimate of 2.4 (95% range 0.00–5.6). A 5-year backtest shows a typical error of ±27.2%, 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 →
20253.00.006.1
20262.80.006.0
20272.70.005.9
20282.60.005.8
20292.40.005.6

Chimney Swift Survey Routes in New Hampshire

Routes recording Chimney Swift 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 →
Dover2220241966
Concord1820241966
Epsom1120231966
Canterbury920241966
Gilmantn I W920241969
Fitzwilliam820221966
Strafford820241966
Lempster820241966
Mt Chocorua520241966
Crawford Not519751967
Walpole420241966
Jefferson Hl420231966
East Kingston420241999
Hopkinton320211966
Stratford320151966
Clarksville320191966
Glen320241975
Wilmot220241966
Milan220241966
Peterborough120241966
Brentwood119981966
Marlow120241966
Franconia120241966
Dixvil Notch119981966
Jeffers Ntch120161995

Chimney Swift Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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