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

Anhinga In Gulf Coastal Prairie

All regionsGulf Coastal PrairieGeneralists

Anhinga in Gulf Coastal Prairie has fallen sharply: down 68% on the route-weighted index since 1970.

-68%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 →
22Routes 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 →
43YearsYears 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 →

Anhinga has fallen sharply in Gulf Coastal Prairie: down 68% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Anhinga in Gulf Coastal Prairie is projected to fall about 99% by 2029 — from 0.24 in 2024 to a central estimate of 0.00 (95% range 0.00–0.94). A 5-year backtest shows a typical error of ±100.7%, with 100% of held-out values landing inside the 95% band.

-99%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 →
0.00Projected 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 →
0.00–0.9495% 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 →
±100.7%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, Anhinga in Gulf Coastal Prairie is projected to fall about 99% by 2029 — from 0.24 in 2024 to a central estimate of 0.00 (95% range 0.00–0.94). A 5-year backtest shows a typical error of ±100.7%, 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 →
20250.050.000.99
20260.040.000.98
20270.030.000.97
20280.010.000.96
20290.000.000.94

Routes In Gulf Coastal Prairie

Routes recording Anhinga 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 →
PetronilaTEXAS81975
Loyola Beach 2TEXAS52022
Moon Lake 2TEXAS32024
Goliad PrairieTEXAS32015
EstherLOUISIANA22008
MauriceLOUISIANA22022
Forked IslandLOUISIANA22018
Hinkles FerTEXAS22021
HackberryLOUISIANA12014
GlencoeLOUISIANA12014
Sabine Nwr 2LOUISIANA12016
WoodlawnLOUISIANA12018
WinnieTEXAS12013
StowellTEXAS12012
DanburyTEXAS12022
KatyTEXAS12024
Rock IslandTEXAS12023
Loyola BeachTEXAS12006
Port AcresTEXAS12024
Moon LakeTEXAS12009
L. Atascosa NwrTEXAS12022
Padre Island PaisTEXAS12015

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