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

Pied-billed Grebe In Tamaulipan Brushlands

All regionsTamaulipan BrushlandsWetland birds

Pied-billed Grebe in Tamaulipan Brushlands has fallen sharply: down 70% on the route-weighted index since 1970.

-70%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 →
9Routes 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 →
21YearsYears 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 →

Pied-billed Grebe has fallen sharply in Tamaulipan Brushlands: down 70% on the route-weighted index since 1970.

Pied-billed Grebe In Tamaulipan Brushlands Population Forecast

If the recent trend holds, Pied-billed Grebe in Tamaulipan Brushlands is projected to fall about 92% by 2026 — from 0.11 in 2021 to a central estimate of 0.01 (95% range 0.00–0.65). A 5-year backtest shows a typical error of ±114.7%, with 100% of held-out values landing inside the 95% band.

-92%Change by 2026TrendPercent 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 →
0.01Projected 2026 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.6595% 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 →
±114.7%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, Pied-billed Grebe in Tamaulipan Brushlands is projected to fall about 92% by 2026 — from 0.11 in 2021 to a central estimate of 0.01 (95% range 0.00–0.65). A 5-year backtest shows a typical error of ±114.7%, with 100% of held-out values landing inside the 95% band.19672026
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 →
20220.040.000.68
20230.030.000.67
20240.030.000.67
20250.020.000.66
20260.010.000.65

Routes In Tamaulipan Brushlands

Routes recording Pied-billed Grebe 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 →
ZapataTEXAS31968
RaymondvilleTEXAS31981
George WestTEXAS21994
Catarina 2TEXAS22013
RachalTEXAS12012
KingsvilleTEXAS11992
RandadoTEXAS11967
CatarinaTEXAS12010
HondoTEXAS12021

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