BirdAnalyst
Species · BCR 34 · BBS 2025 Release · 1966–2024

Loggerhead Shrike In Sierra Madre Occidental

All regionsSierra Madre OccidentalGeneralists

Loggerhead Shrike in Sierra Madre Occidental has fallen sharply: down 60% on the route-weighted index since 1970.

-60%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 →
23Routes 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 fallen sharply in Sierra Madre Occidental: down 60% on the route-weighted index since 1970.

Loggerhead Shrike In Sierra Madre Occidental Population Forecast

If the recent trend holds, Loggerhead Shrike in Sierra Madre Occidental is projected to fall about 76% by 2029 — from 1.4 in 2024 to a central estimate of 0.33 (95% range 0.00–1.9). A 5-year backtest shows a typical error of ±61.2%, with 100% of held-out values landing inside the 95% band.

-76%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 →
0.33Projected 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 →
0.00–1.995% 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 →
±61.2%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 Sierra Madre Occidental is projected to fall about 76% by 2029 — from 1.4 in 2024 to a central estimate of 0.33 (95% range 0.00–1.9). A 5-year backtest shows a typical error of ±61.2%, 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 →
20250.430.002.0
20260.410.002.0
20270.380.002.0
20280.360.002.0
20290.330.001.9

Routes In Sierra Madre Occidental

Routes recording Loggerhead Shrike in Sierra Madre Occidental.
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 →
Mormon LakeARIZONA91974
San SimonARIZONA72024
SunizonaARIZONA51997
Sunizona 2ARIZONA42024
Peña BlancaARIZONA32024
Bartlett ResARIZONA32024
CutterARIZONA32014
SahuaritaARIZONA32021
RuckerARIZONA32009
Forest LakesARIZONA22023
RedingtonARIZONA22007
Carr MtnARIZONA22024
Vicks PeakNEW-MEXICO22024
MagdalenaNEW-MEXICO22024
PomereneARIZONA12017
PatagoniaARIZONA12023
MaineARIZONA11997
Skull ValleyARIZONA12023
AmadoARIZONA12016
McnealARIZONA12024
Clay SpringARIZONA12024
PortalARIZONA11993
DragoonARIZONA12009

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