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

Least Bittern In Gulf Coastal Prairie

All regionsGulf Coastal PrairieWetland birds

Least Bittern in Gulf Coastal Prairie has surged: up 443% on the route-weighted index since 1970.

+443%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 →
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 →
53YearsYears 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 increasecomputed 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 →

Least Bittern has surged in Gulf Coastal Prairie: up 443% on the route-weighted index since 1970.

Least Bittern In Gulf Coastal Prairie Population Forecast

If the recent trend holds, Least Bittern in Gulf Coastal Prairie is projected to fall about 39% by 2030 — from 2.1 in 2025 to a central estimate of 1.3 (95% range 0.47–2.1). A 5-year backtest shows a typical error of ±51.6%, with 60% of held-out values landing inside the 95% band.

-39%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 →
1.3Projected 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 →
0.47–2.195% 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 →
±51.6%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, Least Bittern in Gulf Coastal Prairie is projected to fall about 39% by 2030 — from 2.1 in 2025 to a central estimate of 1.3 (95% range 0.47–2.1). A 5-year backtest shows a typical error of ±51.6%, with 60% of held-out values landing inside the 95% band.19672030
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 →
20261.20.402.0
20271.20.422.0
20281.20.432.0
20291.30.452.1
20301.30.472.1

Routes In Gulf Coastal Prairie

Routes recording Least Bittern 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 →
Forked IslandLOUISIANA342025
Forked Island 2LOUISIANA192011
Ltl ChenierLOUISIANA92025
Sabine Nwr 2LOUISIANA52017
KaplanLOUISIANA42022
Sabine NwrLOUISIANA42008
CreoleLOUISIANA31980
Ltl Chenier 2LOUISIANA32011
Grand IsleLOUISIANA22019
Gran ChenierLOUISIANA11982
HackberryLOUISIANA12016
GlencoeLOUISIANA12012
EstherLOUISIANA12025
MauriceLOUISIANA12010
Lag AtascosaTEXAS11994
IndianolaTEXAS12023
WinnieTEXAS12025
StowellTEXAS12010
DanburyTEXAS11989
KatyTEXAS12013
Rock IslandTEXAS12024
ChinquapinTEXAS12024
Oyster LakeTEXAS12019
Port AcresTEXAS12008
Moon LakeTEXAS12002

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