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

House Sparrow Population Trend in California

All statesGeneralists

House Sparrow in California has fallen sharply: down 55% on the route-weighted index since 1970.

-55%Since 1970TrendPercent 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 →
204Routes 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 →
56YearsYears 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 CaliforniaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc declinecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

House Sparrow has fallen sharply in California: down 55% on the route-weighted index since 1970.

House Sparrow Population Forecast in California

If the recent trend holds, House Sparrow in California is projected to fall about 61% by 2029 — from 16 in 2024 to a central estimate of 6.1 (95% range 0.00–17). A 5-year backtest shows a typical error of ±56.8%, with 80% of held-out values landing inside the 95% band.

-61%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 →
6.1Projected 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 →
0.00–1795% 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 →
±56.8%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 California is projected to fall about 61% by 2029 — from 16 in 2024 to a central estimate of 6.1 (95% range 0.00–17). A 5-year backtest shows a typical error of ±56.8%, with 80% of held-out values landing inside the 95% band.19682029
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 →
20258.20.0019
20267.70.0019
20277.20.0018
20286.70.0018
20296.10.0017

House Sparrow Survey Routes in California

Routes recording House Sparrow in California.
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 →
Atwater75520121972
Orland20820221974
Oroville16620241972
Tipton15319971972
Glenn12320231972
Gravesboro11119951968
Moreno11020241968
Dorris10520191972
Willow Spgs9519811968
Shafter9419891971
Joshua Tree 29020162013
Redding8519831972
Livermore8319911972
Ora Loma8220241973
Caruthers7819871972
San Ysidro7520191973
Willow Springs 27220242013
Hughson7020241968
Athlone6820071973
Collegeville6720041968
Westley6720241972
Lenwood6620121973
Joshua Tree6320021970
Buena Vista5920191990
Auburn5819801969

House Sparrow Population Trend in Other States

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

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