BirdAnalyst
Species · BCR 36 · BBS 2025 Release · 1966–2024

Curve-billed Thrasher In Tamaulipan Brushlands

All regionsTamaulipan BrushlandsArid-land birds

Curve-billed Thrasher in Tamaulipan Brushlands has collapsed: down 75% on the route-weighted index since 1969.

-75%Since 1969TrendPercent 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 →
27Routes 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 →
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 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 →

Curve-billed Thrasher has collapsed in Tamaulipan Brushlands: down 75% on the route-weighted index since 1969.

Curve-billed Thrasher In Tamaulipan Brushlands Population Forecast

If the recent trend holds, Curve-billed Thrasher in Tamaulipan Brushlands is projected to fall about 52% by 2029 — from 4.2 in 2024 to a central estimate of 2.0 (95% range 0.00–7.3). A 5-year backtest shows a typical error of ±25.5%, with 100% of held-out values landing inside the 95% band.

-52%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 →
2.0Projected 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 →
0.00–7.395% 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 →
±25.5%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 Tamaulipan Brushlands is projected to fall about 52% by 2029 — from 4.2 in 2024 to a central estimate of 2.0 (95% range 0.00–7.3). A 5-year backtest shows a typical error of ±25.5%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20252.40.007.7
20262.30.007.6
20272.20.007.5
20282.10.007.4
20292.00.007.3

Routes In Tamaulipan Brushlands

Routes recording Curve-billed Thrasher in Tamaulipan Brushlands.
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 →
MillettTEXAS142012
Millett 2TEXAS132024
EncinalTEXAS122010
Cavasara Cr.TEXAS102023
GuerraTEXAS92018
Agua NuevaTEXAS82023
George WestTEXAS82024
Encinal 2TEXAS72024
RandadoTEXAS62024
Catarina 2TEXAS62017
RachalTEXAS52023
El SauzTEXAS52023
ZapataTEXAS41987
RaymondvilleTEXAS42024
Pedro CreekTEXAS42005
KingsvilleTEXAS32024
Mirando CityTEXAS32024
CatarinaTEXAS32010
DilleyTEXAS32023
SejitaTEXAS32024
La PryorTEXAS22010
Catarina 3TEXAS22024
ProgresoTEXAS21995
San YgnacioTEXAS11985
HondoTEXAS12024

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