BirdAnalyst
Species · Connecticut · BBS 2025 Release · 1966–2024

Swamp Sparrow Population Trend in Connecticut

All statesGeneralists

Swamp Sparrow in Connecticut has edged up: up 21% on the route-weighted index since 1969.

+21%Since 1969TrendPercent 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 →
20Routes 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 →
57YearsYears 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 ConnecticutNotable 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 Connecticut. See the full index history below.

Swamp Sparrow Population Forecast in Connecticut

If the recent trend holds, Swamp Sparrow in Connecticut is projected to rise about 84% by 2029 — from 1.0 in 2024 to a central estimate of 1.8 (95% range 0.00–3.7). A 5-year backtest shows a typical error of ±57.8%, with 100% of held-out values landing inside the 95% band.

+84%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 →
1.8Projected 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 →
0.00–3.795% 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 →
±57.8%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 Connecticut is projected to rise about 84% by 2029 — from 1.0 in 2024 to a central estimate of 1.8 (95% range 0.00–3.7). A 5-year backtest shows a typical error of ±57.8%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20251.80.003.7
20261.80.003.7
20271.80.003.7
20281.80.003.7
20291.80.003.7

Swamp Sparrow Survey Routes in Connecticut

Routes recording Swamp Sparrow in Connecticut.
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 →
Warren3420111972
Buckingham520041972
Warren 2520242017
Woodstock 2320242016
Woodstock220031968
Willimantic219981967
New Hartford219871974
Mystic120231980
E Hartland119891968
Uncasville119931993
Westbrook119941977
No Woodbury120221967
Sherman120161974
Greenwich119901978
Danbury120231975
Long Hill119841981
Mid Haddam120211983
Southington119841977
New Hartford120211998
Granby120241991

Swamp Sparrow Population Trend in Other States

delawareillinoisindianaiowamainemarylandmassachusettsmichiganminnesotanebraskanew-hampshirenew-jerseynew-yorknorth-dakotaohiopennsylvaniarhode-islandsouth-dakotavermontvirginiawest-virginiawisconsin

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