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

Loggerhead Shrike In Coastal California

All regionsCoastal CaliforniaGeneralists

Loggerhead Shrike in Coastal California has collapsed: down 85% on the route-weighted index since 1970.

-85%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 →
89Routes 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 →

Loggerhead Shrike has collapsed in Coastal California: down 85% on the route-weighted index since 1970.

Loggerhead Shrike In Coastal California Population Forecast

If the recent trend holds, Loggerhead Shrike in Coastal California is projected to fall about 84% by 2029 — from 0.98 in 2024 to a central estimate of 0.16 (95% range 0.00–2.5). A 5-year backtest shows a typical error of ±53.7%, with 100% of held-out values landing inside the 95% band.

-84%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 →
0.16Projected 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 →
0.00–2.595% 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 →
±53.7%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, Loggerhead Shrike in Coastal California is projected to fall about 84% by 2029 — from 0.98 in 2024 to a central estimate of 0.16 (95% range 0.00–2.5). A 5-year backtest shows a typical error of ±53.7%, 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 →
20250.390.002.7
20260.330.002.6
20270.270.002.6
20280.210.002.5
20290.160.002.5

Routes In Coastal California

Routes recording Loggerhead Shrike 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 →
ShafterCALIFORNIA181989
TranquillityCALIFORNIA162004
AtwaterCALIFORNIA142012
RiovistaCALIFORNIA112024
VentucopaCALIFORNIA112002
Buena VistaCALIFORNIA72019
S CatalinaCALIFORNIA62019
MaricopaCALIFORNIA62024
Hollister 2CALIFORNIA62024
HollisterCALIFORNIA52011
Elizabeth LkCALIFORNIA51984
Carrizo PlnCALIFORNIA52023
Ora LomaCALIFORNIA52024
Cal Hot SpgsCALIFORNIA51994
Tracy 2CALIFORNIA52024
ColmaCALIFORNIA41968
MorenoCALIFORNIA42024
AuburnCALIFORNIA41980
PowayCALIFORNIA41980
SangerCALIFORNIA42023
Green ValleyCALIFORNIA42017
Lake Hemet 2CALIFORNIA41993
Tres Pinos 2CALIFORNIA42011
RumseyCALIFORNIA32007
HughsonCALIFORNIA32024

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