BirdAnalyst
Species · BCR 33 · BBS 2025 Release · 1966–2024

Loggerhead Shrike In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsGeneralists

Loggerhead Shrike in Sonoran and Mojave Deserts has collapsed: down 84% on the route-weighted index since 1970.

-84%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 →
86Routes 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 Sonoran and Mojave Deserts: down 84% on the route-weighted index since 1970.

Loggerhead Shrike In Sonoran and Mojave Deserts Population Forecast

If the recent trend holds, Loggerhead Shrike in Sonoran and Mojave Deserts is projected to fall about 50% by 2029 — from 2.0 in 2024 to a central estimate of 1.0 (95% range 0.00–5.4). A 5-year backtest shows a typical error of ±32.7%, with 100% of held-out values landing inside the 95% band.

-50%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 →
1.0Projected 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 →
0.00–5.495% 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 →
±32.7%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 Sonoran and Mojave Deserts is projected to fall about 50% by 2029 — from 2.0 in 2024 to a central estimate of 1.0 (95% range 0.00–5.4). A 5-year backtest shows a typical error of ±32.7%, 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 →
20251.30.005.7
20261.20.005.6
20271.20.005.5
20281.10.005.4
20291.00.005.4

Routes In Sonoran and Mojave Deserts

Routes recording Loggerhead Shrike in Sonoran and Mojave Deserts.
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 →
OnyxCALIFORNIA172015
BlytheCALIFORNIA171979
Squaw PeakARIZONA151970
OatmanARIZONA132019
GoldstoneCALIFORNIA132009
Willow SpgsCALIFORNIA101981
Cabeza PrietARIZONA92024
Valley WellsCALIFORNIA92023
Havasu LakeCALIFORNIA81978
Cibola LakeARIZONA72024
Gila BendARIZONA72024
Bates WellARIZONA72023
Ash MeadowsNEVADA72024
VicksburgARIZONA61989
RivieraARIZONA52024
WickenburgARIZONA52023
BeattyNEVADA52017
Anza BorregoCALIFORNIA42024
Kelso ValleyCALIFORNIA42024
New RiverARIZONA32016
DatelandARIZONA32021
LukevilleARIZONA31980
Hope 2ARIZONA32019
InyokernCALIFORNIA32023
TecopaCALIFORNIA32021

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