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

Clapper Rail Population Trend in South Carolina

All statesWetland birds

Clapper Rail in South Carolina has fallen sharply: down 75% on the route-weighted index since 1968.

-75%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 →
3Routes 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 →
28YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Clapper Rail 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 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 →

Clapper Rail has fallen sharply in South Carolina: down 75% on the route-weighted index since 1968.

Clapper Rail Population Forecast in South Carolina

If the recent trend holds, Clapper Rail in South Carolina is projected to fall about 92% by 2028 — from 0.09 in 2023 to a central estimate of 0.01 (95% range 0.00–0.38). A 5-year backtest shows a typical error of ±48.1%, with 100% of held-out values landing inside the 95% band.

-92%Change by 2028TrendPercent 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 →
0.01Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.3895% 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 →
±48.1%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, Clapper Rail in South Carolina is projected to fall about 92% by 2028 — from 0.09 in 2023 to a central estimate of 0.01 (95% range 0.00–0.38). A 5-year backtest shows a typical error of ±48.1%, with 100% of held-out values landing inside the 95% band.19662028
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 →
20240.030.000.40
20250.020.000.39
20260.020.000.39
20270.010.000.38
20280.010.000.38

Clapper Rail Survey Routes in South Carolina

Routes recording Clapper Rail 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 →
Dale420131998
Kiawah Island220231998
Johns Isle119751966

Clapper Rail Population Trend in Other States

alabamaconnecticutdelawarefloridageorgialouisianamarylandnew-jerseynew-yorknorth-carolinatexasvirginia

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