BirdAnalyst
Species · South Carolina · BBS 2026 Release · 1966–2025

Purple Martin Population Trend in South Carolina

All statesAerial insectivores

Purple Martin in South Carolina has fallen sharply: down 61% on the route-weighted index since 1968.

-61%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 →
59YearsYears 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 61% 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 83% by 2030 — from 5.8 in 2025 to a central estimate of 11 (95% range 0.00–23). A 5-year backtest shows a typical error of ±92.4%, with 100% of held-out values landing inside the 95% band.

+83%Change by 2030TrendPercent 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 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–2395% 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 →
±92.4%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, Purple Martin in South Carolina is projected to rise about 83% by 2030 — from 5.8 in 2025 to a central estimate of 11 (95% range 0.00–23). A 5-year backtest shows a typical error of ±92.4%, with 100% of held-out values landing inside the 95% band.19662030
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 →
2026110.0023
2027110.0023
2028110.0023
2029110.0023
2030110.0023

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 Hill2620251973
Coward2320251966
Boykin Ml Pd2219681967
Dillon2020211970
Pinewood1820141998
Pendleton1619761966
Bishopville1520251974
Salem Xrd1520171982
Foreston1320251966
Plum Branch1320251977
Nixville1120171998
Greenwood1020251999
Johns Isle919791966
Wagener920241966
Red Bluff820251996
Hardeeville720251967
Green Sea720252019
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 2026-08-14.