BirdAnalyst
Species · BCR 37 · BBS 2025 Release · 1966–2024

Curve-billed Thrasher In Gulf Coastal Prairie

All regionsGulf Coastal PrairieArid-land birds

Curve-billed Thrasher in Gulf Coastal Prairie has collapsed: down 76% on the route-weighted index since 1970.

-76%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 →
48YearsYears 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 Gulf Coastal Prairie: down 76% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Curve-billed Thrasher in Gulf Coastal Prairie is projected to rise about 142% by 2029 — from 0.10 in 2024 to a central estimate of 0.23 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±205.8%, with 100% of held-out values landing inside the 95% band.

+142%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 →
0.23Projected 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 →
0.00–0.5395% 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 →
±205.8%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 rise about 142% by 2029 — from 0.10 in 2024 to a central estimate of 0.23 (95% range 0.00–0.53). A 5-year backtest shows a typical error of ±205.8%, 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 →
20250.230.000.53
20260.230.000.53
20270.230.000.53
20280.230.000.53
20290.230.000.53

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 →
San PedroTEXAS52017
Lag AtascosaTEXAS22024
Loyola Beach 2TEXAS22016
PetronilaTEXAS12003
IndianolaTEXAS12014
Loyola BeachTEXAS12009
L. Atascosa NwrTEXAS12022

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