BirdAnalyst
Species · California · BBS 2026 Release · 1966–2025

Grasshopper Sparrow Population Trend in California

All statesGrassland birds

Grasshopper Sparrow in California has surged: up 77% on the route-weighted index since 1974.

+77%Since 1974TrendPercent 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 →
61Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Grasshopper 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 Grasshopper Sparrow in California. See the full index history below.

Grasshopper Sparrow Population Forecast in California

If the recent trend holds, Grasshopper Sparrow in California is projected to rise about 154% by 2030 — from 0.08 in 2025 to a central estimate of 0.21 (95% range 0.00–0.50). A 5-year backtest shows a typical error of ±685.5%, with 100% of held-out values landing inside the 95% band.

+154%Change by 2030TrendPercent 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 →
0.21Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.5095% 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 →
±685.5%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, Grasshopper Sparrow in California is projected to rise about 154% by 2030 — from 0.08 in 2025 to a central estimate of 0.21 (95% range 0.00–0.50). A 5-year backtest shows a typical error of ±685.5%, with 100% of held-out values landing inside the 95% band.19722030
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 →
20260.210.000.50
20270.210.000.50
20280.210.000.50
20290.210.000.50
20300.210.000.50

Grasshopper Sparrow Survey Routes in California

Routes recording Grasshopper 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 →
Alderpoint1620121985
Jofegan1020232006
Mt Shasta719761975
Anza619951995
Rio Dell520071981
Cp. Pendleton520041986
Holmes320081992
Red Bluff320222012
Ventucopa319991994
Carrizo Pln320031995
Riovista320142014
Tres Pinos320021974
Laytonville320121974
Martins Fy320081977
Carmel Val320221984
Honeydew220171991
Santa Cruz I219881988
Creston220081983
Jofegan 2220252024
Crowley Lake219771972
Jackson219791979
Cedarville219821982
Hollister219911986
Morro Bay220131979
Tres Pinos 2220112006

Grasshopper Sparrow Population Trend in Other States

alabamaarizonaarkansascoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.