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

Song Sparrow Population Trend in Connecticut

All statesGeneralists

Song Sparrow in Connecticut has declined: down 33% on the route-weighted index since 1968.

-33%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 →
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 →
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 Song 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 Song Sparrow in Connecticut. See the full index history below.

Song Sparrow Population Forecast in Connecticut

If the recent trend holds, Song Sparrow in Connecticut is projected to fall about 18% by 2029 — from 24 in 2024 to a central estimate of 20 (95% range 13–27). A 5-year backtest shows a typical error of ±9.8%, with 100% of held-out values landing inside the 95% band.

-18%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 →
20Projected 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 →
13–2795% 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 →
±9.8%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, Song Sparrow in Connecticut is projected to fall about 18% by 2029 — from 24 in 2024 to a central estimate of 20 (95% range 13–27). A 5-year backtest shows a typical error of ±9.8%, 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 →
2025201328
2026201327
2027201327
2028201327
2029201327

Song Sparrow Survey Routes in Connecticut

Routes recording Song 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 →
Warren8020111972
Sherman5120191972
Long Hill4220191972
Southington3520241973
Danbury3320231968
Willimantic3120181967
Greenwich3120181967
Warren 22920242012
E Hartland2719921966
No Woodbury2720241967
Uncasville2420241973
Mid Haddam2320241973
Woodstock 22320242016
Granby2320241988
Westbrook2120241969
New Hartford2019871972
Mystic1520231973
Buckingham1220221966
New Hartford1220241994
Woodstock420071968

Song Sparrow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseeutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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