BirdAnalyst
Species · BCR 37 · BBS 2026 Release · 1966–2025

Curve-billed Thrasher In Gulf Coastal Prairie

All regionsGulf Coastal PrairieArid-land birds

Curve-billed Thrasher in Gulf Coastal Prairie has fallen sharply: down 57% on the route-weighted index since 1970.

-57%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 →
7Routes 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 →
49YearsYears 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 fallen sharply in Gulf Coastal Prairie: down 57% on the route-weighted index since 1970.

Curve-billed Thrasher In Gulf Coastal Prairie Population Forecast

If the recent trend holds, Curve-billed Thrasher in Gulf Coastal Prairie is projected to fall about 34% by 2030 — from 0.36 in 2025 to a central estimate of 0.24 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±173.1%, with 100% of held-out values landing inside the 95% band.

-34%Change by 2030TrendPercent 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 →
0.24Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.5395% 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 →
±173.1%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 Gulf Coastal Prairie is projected to fall about 34% by 2030 — from 0.36 in 2025 to a central estimate of 0.24 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±173.1%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.240.000.54
20270.240.000.54
20280.240.000.54
20290.240.000.53
20300.240.000.53

Routes In Gulf Coastal Prairie

Routes recording Curve-billed Thrasher in Gulf Coastal Prairie.
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 →
Lag AtascosaTEXAS42025
San PedroTEXAS22025
PetronilaTEXAS12003
IndianolaTEXAS12014
Loyola BeachTEXAS12009
Loyola Beach 2TEXAS12025
L. Atascosa NwrTEXAS12025

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.