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

Grasshopper Sparrow In Coastal California

All regionsCoastal CaliforniaGrassland birds

Grasshopper Sparrow in Coastal California has surged: up 615% on the route-weighted index since 1974.

+615%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 →
37Routes 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 →
51YearsYears 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 increasecomputed 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 →

Grasshopper Sparrow has surged in Coastal California: up 615% on the route-weighted index since 1974.

Grasshopper Sparrow In Coastal California Population Forecast

If the recent trend holds, Grasshopper Sparrow in Coastal California is projected to rise about 437% by 2029 — from 0.06 in 2024 to a central estimate of 0.34 (95% range 0.00–0.86). A 5-year backtest shows a typical error of ±508.6%, with 100% of held-out values landing inside the 95% band.

+437%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 →
0.34Projected 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 →
0.00–0.8695% 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 →
±508.6%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, Grasshopper Sparrow in Coastal California is projected to rise about 437% by 2029 — from 0.06 in 2024 to a central estimate of 0.34 (95% range 0.00–0.86). A 5-year backtest shows a typical error of ±508.6%, with 100% of held-out values landing inside the 95% band.19722029
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 →
20250.340.000.85
20260.340.000.86
20270.340.000.86
20280.340.000.86
20290.340.000.86

Routes In Coastal California

Routes recording Grasshopper Sparrow 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 →
JofeganCALIFORNIA102023
AnzaCALIFORNIA61995
Cp. PendletonCALIFORNIA52004
Red BluffCALIFORNIA32022
RiovistaCALIFORNIA32014
Tres PinosCALIFORNIA32002
Carmel ValCALIFORNIA32022
VentucopaCALIFORNIA31999
Carrizo PlnCALIFORNIA32003
HollisterCALIFORNIA21991
Morro BayCALIFORNIA22013
Elsinore MtnCALIFORNIA22022
Santa Cruz ICALIFORNIA21988
CrestonCALIFORNIA22008
JacksonCALIFORNIA21979
Tres Pinos 2CALIFORNIA22011
Jofegan 2CALIFORNIA22024
HughsonCALIFORNIA11996
Yokohl ValCALIFORNIA11996
Santa YnezCALIFORNIA11994
Orange CoveCALIFORNIA12006
Point ReyesCALIFORNIA12023
FairfaxCALIFORNIA12007
FolsomCALIFORNIA11984
El ToroCALIFORNIA11986

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