BirdAnalyst
Species · South Carolina · BBS 2025 Release · 1966–2024

Anhinga Population Trend in South Carolina

All statesGeneralists

Anhinga in South Carolina has surged: up 128% on the route-weighted index since 1976.

+128%Since 1976TrendPercent 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 →
14Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
31YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Anhinga Trends in South CarolinaNotable 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 →

Anhinga has surged in South Carolina: up 128% on the route-weighted index since 1976.

Anhinga Population Forecast in South Carolina

If the recent trend holds, Anhinga in South Carolina is projected to rise about 172% by 2029 — from 0.10 in 2024 to a central estimate of 0.26 (95% range 0.00–0.55). A 5-year backtest shows a typical error of ±78.4%, with 100% of held-out values landing inside the 95% band.

+172%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 →
0.26Projected 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 →
0.00–0.5595% 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 →
±78.4%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 South Carolina is projected to rise about 172% by 2029 — from 0.10 in 2024 to a central estimate of 0.26 (95% range 0.00–0.55). A 5-year backtest shows a typical error of ±78.4%, with 100% of held-out values landing inside the 95% band.19732029
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 →
20250.240.000.54
20260.250.000.54
20270.250.000.54
20280.250.000.55
20290.260.000.55

Anhinga Survey Routes in South Carolina

Routes recording Anhinga in South Carolina.
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 →
Bennettsville2120171999
Nixville320092009
Kiawah Island220242000
Walterboro219751975
Jamestown120042004
Hardeeville120231973
Rome120231980
Holly Hill120211988
Adams Run120231996
Red Bluff120232018
Bishopville120232007
Olar120182018
Pinewood120171998
Dale120231998

Anhinga Population Trend in Other States

alabamaarkansasfloridageorgialouisianamississippinorth-carolinaoklahomatexasvirginia

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