BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Anhinga

AnhingidaeWetland birdsAnhinga anhinga

Anhinga has increased: up 48% on the route-weighted index since 1968.

+48%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 →
316RoutesSurvey 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 Anhinga

The Anhinga (Anhinga anhinga) is a North American member of the Anhingas (Anhingidae). In this analysis it is grouped with the wetland birds.

Size
29.5–37.5 in long (75–95 cm) — a large waterbird (typical for the family)
Habitat
Marshes, ponds, lakeshores and other freshwater wetlands.
Diet
Aquatic invertebrates, small fish, frogs and plant matter.
Range
Recorded on 316 Breeding Bird Survey routes across 11 states, most concentrated in the Southeastern Coastal Plain.
Family
Anhingidae · Wetland birds

Notable Anhinga 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 Anhinga. See the full index history below.

Anhinga Population Forecast

If the recent trend holds, Anhinga is projected to rise about 53% by 2029 — from 0.06 in 2024 to a central estimate of 0.08 (95% range 0.04–0.12). A 5-year backtest shows a typical error of ±25.2%, with 100% of held-out values landing inside the 95% band.

+53%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 →
0.08Projected 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 →
0.04–0.1295% 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 →
±25.2%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 is projected to rise about 53% by 2029 — from 0.06 in 2024 to a central estimate of 0.08 (95% range 0.04–0.12). A 5-year backtest shows a typical error of ±25.2%, 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 →
20250.080.040.12
20260.080.040.12
20270.080.040.12
20280.080.040.12
20290.080.040.12

Where the Anhinga Is Detected

BBS routes recording Anhinga, sized by most recent count.

Anhinga Population Trend by State

Anhinga 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+43%197819
Arkansas-66%19935
Florida-14%196895
Georgia-27%196854
Louisiana+160%196949
Mississippi13×197320
North Carolina-23%199917
Oklahomainsufficient datan/a1
South Carolina+128%197614
Texas-73%197040
Virginiainsufficient datan/a2

Anhinga Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Anhinga 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 →
Oaks and Prairies-37%197313
West Gulf Coastal Plain / Ouachitas-73%196930
Mississippi Alluvial Valley+682%197435
Southeastern Coastal Plain+141%1968140
Peninsular Florida-19%196871
Gulf Coastal Prairie-68%197022

Anhinga Conservation Status

Our route-weighted index shows it up about 48% 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.