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

Swamp Sparrow Population Trend in New Hampshire

All statesWetland birds

Swamp Sparrow in New Hampshire has edged down: down 23% on the route-weighted index since 1968.

-23%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 Swamp Sparrow 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 →

No notable trend signals for Swamp Sparrow in New Hampshire. See the full index history below.

Swamp Sparrow Population Forecast in New Hampshire

If the recent trend holds, Swamp Sparrow in New Hampshire is projected to stay roughly flat through 2030, near 1.9 (95% range 0.86–2.9). A 5-year backtest shows a typical error of ±14.7%, with 100% of held-out values landing inside the 95% band.

-3%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 →
1.9Projected 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 →
0.86–2.995% 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 →
±14.7%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, Swamp Sparrow in New Hampshire is projected to stay roughly flat through 2030, near 1.9 (95% range 0.86–2.9). A 5-year backtest shows a typical error of ±14.7%, with 100% 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 →
20261.90.872.9
20271.90.872.9
20281.90.872.9
20291.90.862.9
20301.90.862.9

Swamp Sparrow Survey Routes in New Hampshire

Routes recording Swamp Sparrow 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 →
Walpole520251966
Marlow520251966
Lempster520251966
Milan520251966
Wilmot420251966
Mt Chocorua320251970
Dixvil Notch320161966
Peterborough220251966
Fitzwilliam220251966
Concord220231968
Gilmantn I W220231969
Franconia220251966
Clarksville220251969
Jeffers Ntch220251998
Dixville Notch 2220252018
Brentwood119981966
Dover120211967
Hopkinton120251966
Epsom120231966
Strafford120231966
Canterbury120251967
Crawford Not119661966
Jefferson Hl120251966
Stratford120251966
Glen120251975

Swamp Sparrow Population Trend in Other States

connecticutdelawareillinoisindianaiowamainemarylandmassachusettsmichiganminnesotanebraskanew-jerseynew-yorknorth-dakotaohiopennsylvaniarhode-islandsouth-dakotavermontvirginiawest-virginiawisconsin

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