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

Song Sparrow Population Trend in California

All statesGeneralists

Song Sparrow in California has increased: up 29% on the route-weighted index since 1970.

+29%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 →
205Routes 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 Song 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 →

No notable trend signals for Song Sparrow in California. See the full index history below.

Song Sparrow Population Forecast in California

If the recent trend holds, Song Sparrow in California is projected to rise about 19% by 2029 — from 4.6 in 2024 to a central estimate of 5.5 (95% range 3.4–7.7). A 5-year backtest shows a typical error of ±51.4%, with 60% of held-out values landing inside the 95% band.

+19%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 →
5.5Projected 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 →
3.4–7.795% 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 →
±51.4%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, Song Sparrow in California is projected to rise about 19% by 2029 — from 4.6 in 2024 to a central estimate of 5.5 (95% range 3.4–7.7). A 5-year backtest shows a typical error of ±51.4%, with 60% 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 →
20255.53.47.7
20265.53.47.7
20275.53.47.7
20285.53.47.7
20295.53.47.7

Song Sparrow Survey Routes in California

Routes recording Song 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 →
Dorris8420191976
Horse Creek5420191970
Crescent Cty3720241972
Point Reyes3420231970
Rio Dell3120121972
Santa Cruz I3019881988
Honeydew2920171968
Navarro2920111972
Ora Loma2620241972
Staten Is.2620241994
Redwood N.P.2520101995
Harbor Lake 22420242014
Cp. Pendleton2220041970
Genesee2220241972
Fish Rock2120141968
Arvin2020221971
Sisquoc1920141970
Pescadero1920241992
Poway1619801973
Last Chance1520191993
Jofegan 21420242024
Chilcoot1420241998
El Toro1319991973
Macdoel1320191975
Iron Gate1320191988

Song Sparrow Population Trend in Other States

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

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