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

House Sparrow Population Trend in Connecticut

All statesGeneralists

House Sparrow in Connecticut has declined: down 30% on the route-weighted index since 1968.

-30%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 House 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 House Sparrow in Connecticut. See the full index history below.

House Sparrow Population Forecast in Connecticut

If the recent trend holds, House Sparrow in Connecticut is projected to fall about 22% by 2029 — from 22 in 2024 to a central estimate of 17 (95% range 3.2–31). A 5-year backtest shows a typical error of ±29.8%, with 100% of held-out values landing inside the 95% band.

-22%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 →
17Projected 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 →
3.2–3195% 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 →
±29.8%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, House Sparrow in Connecticut is projected to fall about 22% by 2029 — from 22 in 2024 to a central estimate of 17 (95% range 3.2–31). A 5-year backtest shows a typical error of ±29.8%, 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 →
2025184.132
2026183.931
2027173.631
2028173.431
2029173.231

House Sparrow Survey Routes in Connecticut

Routes recording House 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 →
Westbrook7520241969
Mystic7020231973
Danbury4720231968
Willimantic3720181967
Southington3720241973
Mid Haddam2320241973
Sherman2120191972
Granby1720241988
E Hartland1619921966
Buckingham1620221966
No Woodbury1620241967
Woodstock1320071968
Warren1320111972
New Hartford1319871972
Long Hill1120191972
Woodstock 21120242016
Warren 2820242012
Uncasville720241973
Greenwich720181967
New Hartford120241994

House Sparrow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradodelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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