BirdAnalyst
Species · California · BBS 2026 Release · 1966–2025

Loggerhead Shrike Population Trend in California

All statesGrassland birds

Loggerhead Shrike in California has collapsed: down 86% on the route-weighted index since 1970.

-86%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 →
57YearsYears 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 86% 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 2030 — from 1.0 in 2025 to a central estimate of 0.00 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±116.7%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2030TrendPercent 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 2030 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 →
±116.7%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 California is projected to fall about 100% by 2030 — from 1.0 in 2025 to a central estimate of 0.00 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±116.7%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.000.002.4
20270.000.002.4
20280.000.002.4
20290.000.002.4
20300.000.002.4

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
Carrizo Pln1620251970
Tranquillity1620041972
Atwater1420121972
Goldstone1320091968
Riovista1120251968
Ventucopa1120021972
Willow Spgs1019811968
Ora Loma1020251972
Valley Wells920231969
Havasu Lake819781973
Buena Vista720191990
Ravendale620251973
Maricopa620251970
Hollister 2620242012
Hollister520111974
Benton520251982
Elizabeth Lk519841970
Cal Hot Spgs519941993
Tracy 2520242010
Colma419681968
Big Pine420051970
Parkfield420251968

Loggerhead Shrike Population Trend in Other States

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

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.