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

Purple Martin Population Trend in South Carolina

All statesAerial insectivores

Purple Martin in South Carolina has fallen sharply: down 59% on the route-weighted index since 1968.

-59%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 →
50Routes 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Purple Martin 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 →

Purple Martin has fallen sharply in South Carolina: down 59% on the route-weighted index since 1968.

Purple Martin Population Forecast in South Carolina

If the recent trend holds, Purple Martin in South Carolina is projected to rise about 50% by 2029 — from 7.4 in 2024 to a central estimate of 11 (95% range 0.00–24). A 5-year backtest shows a typical error of ±119.7%, with 100% of held-out values landing inside the 95% band.

+50%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 →
11Projected 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 →
0.00–2495% 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 →
±119.7%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, Purple Martin in South Carolina is projected to rise about 50% by 2029 — from 7.4 in 2024 to a central estimate of 11 (95% range 0.00–24). A 5-year backtest shows a typical error of ±119.7%, 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 →
2025110.0024
2026110.0024
2027110.0024
2028110.0024
2029110.0024

Purple Martin Survey Routes in South Carolina

Routes recording Purple Martin 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 →
Blacksburg31220131998
Little Mtn5819881966
Prosperity5320241992
Barton Creek2920221968
Holly Hill2620241973
Boykin Ml Pd2219681967
Dillon2020211970
Pinewood1820141998
Pendleton1619761966
Salem Xrd1520171982
Sandhills1520241994
Foreston1320211966
Owings 21220242005
Nixville1120171998
Joanna1020231999
Red Bluff1020241996
Johns Isle919791966
Wagener920241966
Plum Branch720241977
Salem720232010
Greenwood720161999
Chesnee720151992
Walterboro620171970
Landrum619881980
Lowrys620172017

Purple Martin Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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