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

Loggerhead Shrike Population Trend in California

All statesGeneralists

Loggerhead Shrike in California has collapsed: down 88% on the route-weighted index since 1970.

-88%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 →
156Routes 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 Loggerhead Shrike 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 →

Loggerhead Shrike has collapsed in California: down 88% on the route-weighted index since 1970.

Loggerhead Shrike Population Forecast in California

If the recent trend holds, Loggerhead Shrike in California is projected to fall about 100% by 2029 — from 0.88 in 2024 to a central estimate of 0.00 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±116.8%, 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 →
0.00–2.495% 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 →
±116.8%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 California is projected to fall about 100% by 2029 — from 0.88 in 2024 to a central estimate of 0.00 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±116.8%, 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 →
20250.000.002.4
20260.000.002.4
20270.000.002.4
20280.000.002.4
20290.000.002.4

Loggerhead Shrike Survey Routes in California

Routes recording Loggerhead Shrike 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 →
Shafter1819891971
Onyx1720151968
Blythe1719791973
Tranquillity1620041972
Atwater1420121972
Goldstone1320091968
Ravendale1320241973
Riovista1120241968
Ventucopa1120021972
Willow Spgs1019811968
Valley Wells920231969
Havasu Lake819781973
Buena Vista720191990
S Catalina620191989
Maricopa620241970
Hollister 2620242012
Hollister520111974
Elizabeth Lk519841970
Carrizo Pln520231970
Ora Loma520241972
Cal Hot Spgs519941993
Tracy 2520242010
Colma419681968
Big Pine420051970
Moreno420241968

Loggerhead Shrike Population Trend in Other States

alabamaarizonaarkansascoloradofloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmichiganminnesotamississippimissourimontananebraskanevadanew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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