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

Common Gallinule Population Trend in South Carolina

All statesWetland birds

Common Gallinule in South Carolina has surged: up 175% on the route-weighted index since 2002.

+175%Since 2002TrendPercent 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 →
5Routes 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 →
18YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Common Gallinule 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 →

Common Gallinule has surged in South Carolina: up 175% on the route-weighted index since 2002.

Common Gallinule Population Forecast in South Carolina

If the recent trend holds, Common Gallinule in South Carolina is projected to stay roughly flat through 2029, near 0.20 (95% range 0.00–0.48). A 5-year backtest shows a typical error of ±93.8%, with 100% of held-out values landing inside the 95% band.

+5%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 →
0.20Projected 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 →
0.00–0.4895% 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 →
±93.8%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, Common Gallinule in South Carolina is projected to stay roughly flat through 2029, near 0.20 (95% range 0.00–0.48). A 5-year backtest shows a typical error of ±93.8%, with 100% of held-out values landing inside the 95% band.19772029
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 →
20250.190.000.47
20260.190.000.47
20270.200.000.48
20280.200.000.48
20290.200.000.48

Common Gallinule Survey Routes in South Carolina

Routes recording Common Gallinule 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 →
Dale320242019
Hardeeville120062006
Kiawah Island120241998
Walterboro119771977
Bennettsville120022002

Common Gallinule Population Trend in Other States

alabamaarizonaarkansascaliforniaconnecticutdelawarefloridageorgiaillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippinevadanew-jerseynew-yorknorth-carolinaohiopennsylvaniatennesseetexasutahvermontwisconsin

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