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

Loggerhead Shrike Population Trend in Arizona

All statesGeneralists

Loggerhead Shrike in Arizona has fallen sharply: down 67% on the route-weighted index since 1970.

-67%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 →
76Routes 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 ArizonaNotable 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 fallen sharply in Arizona: down 67% on the route-weighted index since 1970.

Loggerhead Shrike Population Forecast in Arizona

If the recent trend holds, Loggerhead Shrike in Arizona is projected to fall about 31% by 2029 — from 1.8 in 2024 to a central estimate of 1.3 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±25.6%, with 100% of held-out values landing inside the 95% band.

-31%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 →
1.3Projected 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 →
0.00–3.495% 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 →
±25.6%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, Loggerhead Shrike in Arizona is projected to fall about 31% by 2029 — from 1.8 in 2024 to a central estimate of 1.3 (95% range 0.00–3.4). A 5-year backtest shows a typical error of ±25.6%, 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 →
20251.40.003.5
20261.40.003.5
20271.30.003.4
20281.30.003.4
20291.30.003.4

Loggerhead Shrike Survey Routes in Arizona

Routes recording Loggerhead Shrike in Arizona.
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 →
Squaw Peak1519701968
Oatman1320191988
Mormon Lake919741968
Cabeza Priet920241994
San Simon720241969
Bates Well720231995
Cibola Lake720241993
Gila Bend720241995
Seligman720241994
Hunt620181968
Vicksburg619891968
Sunizona519971969
Riviera520241992
Wickenburg520232017
Kaibito420191996
Sunizona 2420242001
The Gap319761968
Rucker320091993
New River320161974
Dateland320211990
Lukeville319801975
Peña Blanca320241975
Cow Springs320171992
Bartlett Res320242000
Cutter320142014

Loggerhead Shrike Population Trend in Other States

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

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