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

Horned Lark Population Trend in California

All statesGrassland birds

Horned Lark in California has fallen sharply: down 74% on the route-weighted index since 1970.

-74%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 →
159Routes 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 Horned Lark 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 →

Horned Lark has fallen sharply in California: down 74% on the route-weighted index since 1970.

Horned Lark Population Forecast in California

If the recent trend holds, Horned Lark in California is projected to fall about 65% by 2029 — from 5.4 in 2024 to a central estimate of 1.9 (95% range 0.00–7.3). A 5-year backtest shows a typical error of ±32.6%, with 100% of held-out values landing inside the 95% band.

-65%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 →
1.9Projected 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 →
0.00–7.395% 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 →
±32.6%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, Horned Lark in California is projected to fall about 65% by 2029 — from 5.4 in 2024 to a central estimate of 1.9 (95% range 0.00–7.3). A 5-year backtest shows a typical error of ±32.6%, with 100% 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 →
20252.80.008.2
20262.60.007.9
20272.30.007.7
20282.10.007.5
20291.90.007.3

Horned Lark Survey Routes in California

Routes recording Horned Lark 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 →
Lane Mtn17519731973
Honey Lake15920241972
Willow Spgs12919811968
Barstow12219981968
Carrizo Pln10020231970
Lenwood8020121973
Calif City6320151977
Ventucopa5820021972
Goumaz5120111997
Clear Lk Res4920181972
Inyokern4520241976
Shafter4519891971
Caruthers4119871972
Ravendale3520241973
Crowley Lake3420241972
Greenwater V3320241972
Athlone2920071972
Hollister2720071976
Lucerne Val2520241974
Wildrose2320221977
Palo Verde2320241974
Ft Irwin2019821975
Santa Cruz I1819881988
Likely1820241971
Willow Springs 21620242013

Horned Lark Population Trend in Other States

alabamaalaskaarizonaarkansascoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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