BirdAnalyst
Species · BCR 32 · BBS 2025 Release · 1966–2024

Horned Lark In Coastal California

All regionsCoastal CaliforniaGrassland birds

Horned Lark in Coastal California has collapsed: down 89% on the route-weighted index since 1970.

-89%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 →
81Routes In RegionSurvey 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 SignalsNotable 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 collapsed in Coastal California: down 89% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Horned Lark in Coastal California is projected to fall about 100% by 2029 — from 1.4 in 2024 to a central estimate of 0.00 (95% range 0.00–7.9). A 5-year backtest shows a typical error of ±43.3%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–7.995% 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 →
±43.3%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 Coastal California is projected to fall about 100% by 2029 — from 1.4 in 2024 to a central estimate of 0.00 (95% range 0.00–7.9). A 5-year backtest shows a typical error of ±43.3%, 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 →
20250.710.008.6
20260.440.008.3
20270.160.008.0
20280.000.007.9
20290.000.007.9

Routes In Coastal California

Routes recording Horned Lark in Coastal 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 →
Carrizo PlnCALIFORNIA1002023
VentucopaCALIFORNIA582002
ShafterCALIFORNIA451989
CaruthersCALIFORNIA411987
AthloneCALIFORNIA292007
HollisterCALIFORNIA272007
Santa Cruz ICALIFORNIA181988
El ToroCALIFORNIA151987
Lake HemetCALIFORNIA151977
TiptonCALIFORNIA141997
JofeganCALIFORNIA112023
Buena VistaCALIFORNIA112019
Staten Is.CALIFORNIA102024
OilfieldsCALIFORNIA92012
AtwaterCALIFORNIA92012
Collegeville 2CALIFORNIA92023
MaricopaCALIFORNIA82024
LockwoodCALIFORNIA82024
Anza 2CALIFORNIA82024
South LakeCALIFORNIA82006
PowayCALIFORNIA61980
GreenfieldCALIFORNIA62024
Mesa GrandeCALIFORNIA52024
Elsinore MtnCALIFORNIA51975
ParkfieldCALIFORNIA42012

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