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

Swamp Sparrow Population Trend in New Hampshire

All statesGeneralists

Swamp Sparrow in New Hampshire has edged down: down 19% on the route-weighted index since 1968.

-19%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 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 rise about 27% by 2029 — from 1.5 in 2024 to a central estimate of 1.9 (95% range 0.86–2.9). A 5-year backtest shows a typical error of ±22.4%, with 100% of held-out values landing inside the 95% band.

+27%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 →
1.9Projected 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 →
0.86–2.995% 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 →
±22.4%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, Swamp Sparrow in New Hampshire is projected to rise about 27% by 2029 — from 1.5 in 2024 to a central estimate of 1.9 (95% range 0.86–2.9). A 5-year backtest shows a typical error of ±22.4%, 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 →
20251.90.873.0
20261.90.873.0
20271.90.863.0
20281.90.862.9
20291.90.862.9

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 →
Wilmot620241966
Marlow620241966
Mt Chocorua420241970
Jefferson Hl320241966
Franconia320231966
Milan320241966
Dixvil Notch320161966
Peterborough220241966
Concord220231968
Canterbury220241967
Gilmantn I W220231969
Stratford220231966
East Kingston220231999
Dixville Notch 2220242018
Brentwood119981966
Fitzwilliam120241966
Dover120211967
Hopkinton120231966
Epsom120231966
Strafford120231966
Walpole120241966
Lempster120241966
Crawford Not119661966
Clarksville120221969
Glen120241975

Swamp Sparrow Population Trend in Other States

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

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