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

Curve-billed Thrasher In Sierra Madre Occidental

All regionsSierra Madre OccidentalArid-land birds

Curve-billed Thrasher in Sierra Madre Occidental has surged: up 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 →
21Routes 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 increasecomputed 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 →

Curve-billed Thrasher has surged in Sierra Madre Occidental: up 84% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Curve-billed Thrasher in Sierra Madre Occidental is projected to rise about 15% by 2029 — from 2.3 in 2024 to a central estimate of 2.7 (95% range 1.5–3.9). A 5-year backtest shows a typical error of ±35.3%, with 80% of held-out values landing inside the 95% band.

+15%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 →
2.7Projected 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 →
1.5–3.995% 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 →
±35.3%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, Curve-billed Thrasher in Sierra Madre Occidental is projected to rise about 15% by 2029 — from 2.3 in 2024 to a central estimate of 2.7 (95% range 1.5–3.9). A 5-year backtest shows a typical error of ±35.3%, with 80% 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 →
20252.61.43.8
20262.61.43.8
20272.61.43.8
20282.61.43.9
20292.71.53.9

Routes In Sierra Madre Occidental

Routes recording Curve-billed Thrasher 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 →
CutterARIZONA162014
Bartlett ResARIZONA142024
SunizonaARIZONA91997
PatagoniaARIZONA72024
Carr MtnARIZONA72024
PomereneARIZONA62023
SahuaritaARIZONA62024
DragoonARIZONA62009
RedingtonARIZONA52023
AmadoARIZONA52023
Sunizona 2ARIZONA42024
Aztec PeakARIZONA31978
PortalARIZONA22024
Emory PassNEW-MEXICO22012
San SimonARIZONA12024
Peña BlancaARIZONA12023
Mt. GrahamARIZONA12018
McnealARIZONA12024
RuckerARIZONA12007
Vicks PeakNEW-MEXICO12006
MagdalenaNEW-MEXICO12021

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