BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Least Bittern

ArdeidaeWetland birdsBotaurus exilis

Least Bittern has surged: up 97% on the route-weighted index since 1968.

+97%Since 1968TrendPercent 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 →
200RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
58Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Least Bittern

The Least Bittern (Botaurus exilis) is a North American member of the Herons, Egrets & Bitterns (Ardeidae). In this analysis it is grouped with the wetland birds.

Size
12–51 in long (30–130 cm) — a long-legged wader (typical for the family)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Aquatic invertebrates, small fish, frogs and plant matter.
Range
Recorded on 200 Breeding Bird Survey routes across 33 states, most concentrated in the Peninsular Florida.
Family
Ardeidae · Wetland birds

Notable Least Bittern TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Least Bittern. See the full index history below.

Least Bittern Population Forecast

If the recent trend holds, Least Bittern is projected to stay roughly flat through 2029, near 0.02 (95% range 0.01–0.03). A 5-year backtest shows a typical error of ±28.5%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.02Projected 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 →
0.01–0.0395% 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 →
±28.5%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 is projected to stay roughly flat through 2029, near 0.02 (95% range 0.01–0.03). A 5-year backtest shows a typical error of ±28.5%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.020.010.03
20260.020.010.03
20270.020.010.03
20280.020.010.03
20290.020.010.03

Where the Least Bittern Is Detected

BBS routes recording Least Bittern, sized by most recent count.

Least Bittern Population Trend by State

Least Bittern population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alabama-72%197114
Arizona-56%20023
Arkansasinsufficient datan/a1
Californiainsufficient datan/a4
Connecticutinsufficient datan/a2
Delawareinsufficient datan/a2
Florida-55%196836
Georgiainsufficient datan/a3
Illinoisinsufficient datan/a3
Indianainsufficient datan/a1
Iowainsufficient datan/a1
Kansasinsufficient datan/a3
Louisiana+302%197018
Maryland+182%19694
Michigan-53%19789
Minnesota-35%197614
Mississippiinsufficient datan/a4
Missouriinsufficient datan/a2
Nebraskainsufficient datan/a2
Nevadainsufficient datan/a1
New Hampshireinsufficient datan/a2
New Jerseyinsufficient datan/a2
New Yorkinsufficient datan/a7
North Carolina-77%19747
North Dakotainsufficient datan/a9
Ohioinsufficient datan/a1
Oregoninsufficient datan/a1
South Carolinainsufficient datan/a1
South Dakotainsufficient datan/a3
Texas-51%197117
Vermontinsufficient datan/a4
Virginiainsufficient datan/a1
Wisconsin+17%197318

Least Bittern Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Least Bittern population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Prairie Potholes+135%200418
Prairie Hardwood Transition-33%197225
Southeastern Coastal Plain-72%196927
New England / Mid-Atlantic Coast+165%196911
Peninsular Florida-67%196832
Sonoran and Mojave Deserts-41%20016
Gulf Coastal Prairie+276%197027

Least Bittern Conservation Status

Our route-weighted index shows it up about 97% since 1968.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.