The Inland Range of the Ivory-billed Woodpecker in South Carolina; an Ecological Perspective.

Out of convenience, and obtuseness that empirical ornithology did not exist centuries ago the Ivory-billed Woodpeckers' precontact and historical range in South Carolina and other states has been placed at the Fall Line.

South Carolina Sprunt and Chamberlain (1949) suggest that Ivory-billed Woodpecker was formerly common over much of the eastern part of the state but its virtual extinction was due to the encroachment of civilization.

The original range of Ivory-billed Woodpecker in South Carolina was the extent of the coastal plain bordered to the north by the fall line and extending to the Atlantic coast. This area was comprised of bottomland hardwood riverine systems surrounded by longleaf pine uplands intermixed with farms and plantations.     

Recovery Plan for the Ivory-billed Woodpecker (Campephilus principalis) April, 2010

Most, if not all Congaree National Park, SC's biology researchers are familiar with John Cely. In 2023, he wrote that Ivory-billed Woodpecker (Campephilus principalis; IBWO) locality records extend as far inland as South Carolina’s Fall Line. He espoused that there is no ecological reason to exclude the Congaree River corridor, which lies well below the Fall Line, from the 19th-century IBWO range.

Cely, Page 1 2023

The Fall Line marks a sharp geological transition where the Piedmont’s hard, elevated bedrock gives way to the Coastal Plain’s soft, sandy sediments. While this boundary has substantial ecological implications for “the great chieftain of the woodpecker tribe” (Audubon), it was likely not an absolute barrier to IBWO dispersal or even nesting in landscapes of gradually increasing elevation above the Fall Line. IBWO density was probably lower above the Fall Line than below it across relevant states, because the line also delineates two distinct biotas.

Cely, Page 2 2023

Upon an ecological presentation here, there is no reason precontact Ivory-bills did not inhabit all of the land southeast of the Fall Line in SC. IBWOs likely inhabited some select areas above the Fall Line also (see map within). 

As a facultative omnivore but obligate feeder of larval Coleoptera during the breeding season, IBWO distribution would have been somewhat constrained by beetle density and community composition especially if females have site fidelity which is suspected. Accordingly, breeding range and density should correlate with micro and macrohabitats supporting high biomass of saprophytic Coleopteran larvae and adults. This food limitation likely diminished post-fledging, when parents and altricial young became vagile as a group and could exploit resources at slightly higher latitudes and/or elevations. Proposed is only minor "incursions" of breeding north of the Fall Line; no proposal for large interstate expansion of the IBs historical range is argued.   

In foothill regions, a historical symbiosis with beaver-driven hydrology may have further influenced IBWO occurrence, a hypothesis consistent with the observed pattern of reports and specimens declining with increasing altitude and latitude. Finally, seasonal differentiation in foraging strategy should be considered a potential evolutionary driver for precontact IBWOs.

Post-breeding resource availability may have made it advantageous for Ivory-billed Woodpeckers (Campephilus principalis; IBWO) to avoid depleting select beetle families in lowland habitats. Fruits, nuts, and other insect taxa became more concentrated and accessible from early summer through early December, preceding the subsequent IBWO breeding season from early December to at least April.

Three notable locations with IBWO reports. 1. is referred to by Tanner, Cely and others. 2. summarizes years of modern work by many. 3. is based on reports with some suggestive modern videos. 

Many North American birds shift seasonally with altitude, temperature, and food availability. A U.S. example is the American Dipper (Cinclus mexicanus), which moves to higher-elevation foraging and breeding areas in summer.

The Fall Line creates a sharp ecological divide in South Carolina. Above the line, rivers are faster and narrower, flowing over rocky, clay-rich soils. Below it, rivers slow and widen into floodplains with sandy soils. This transition produces distinct ecosystems and plant communities. The extensive floodplains, slower rivers, and warmer, sandier environments of the Coastal Plain support greater diversity of reptiles, amphibians, other lowland wildlife, and IBWOs.

SC data. Note the winter 10-degree lower average temperature difference between the two areas. Warm blooded animals like IBs face a large increase in energetic costs to survive cold nights. Average temperatures are impactful but extreme temperatures erect not only another barrier for IB breeding, but a lethal one at higher elevations. 

Record cold winter day in SC that shows the potentially fatal temperatures that warm-blooded, omnivores are exposed to. Note the 25 degree drop from the frigid coastal plain to the Appalachians.   Cold Winter 1985

Zoogeographic limitations are often determined by the extremes not the averages. Birds can die in one night from these extremes. There is no evidence that Ivory-bills were a migratory species but seasonal movements were possible and may be the source of some historic higher elevation reports and records.

Typical IBWO range map that roughly adheres to the Fall Line at least in SC.

Consequently, IBWO breeding success and population density was likely higher below the Fall Line, correlating positively with warmer late-winter and early-spring temperatures and increased forest humidity relative to the Piedmont. The inner and outer Coastal Plain, both below the Fall Line, likely supported a denser, richer community of saprophytic beetles than the drier, cooler upland forests above it. 

Multiple studies report positive relationships between invertebrate biomass and temperature, humidity, and lower elevation.

General Humidity Chart, Coleopteran density, community diversity and biomass is positively correlated to humidity.   

However, beavers, which were abundant in the precontact era, may have partially altered this pattern by damming high-energy streams above the Fall Line. Beaver-induced tree mortality would have provided substantial, though spatially constrained, foraging substrate for breeding IBWOs along narrow, linear corridors bordering former stream channels that became ponds. Riverine wetlands, including small rivers, streams, and creeks, thus succeeded into a discontinuous series of lacustrine wetlands such as ponds, bogs, and swamps. These lacustrine systems create dynamic forest ecotones with elevated densities of stressed and standing dead trees.

Critical SC area that portrays an ecological approach to the IBWO breeding range represented by thick blue line. The feather like blue areas delineate precontact riparian/stream corridors likely dammed by beavers, these areas then supporting some IBs. The 3 red dots represent the 3 inland IBWO data points discussed in the text which were near the Fall Line.  

Tanner, 1942 summary of records. Note that 2 is on other unique maps here; that report was close to the Fall Line and may have been a family group inferring nearby breeding. Cely (2023) also brings up the April 1876 record of three IBs. The Santee River is one of the handful of areas that Tanner felt IBs were still occupying circa 1940. Per modern patterns of where 21st century IBs are, evidence, and acceptance of avian site fidelity, Tanner was fairly accurate with the locations he proposed still had IBs in 1939. 

 

The precontact IBWO breeding range in a biological context may have resembled a hand, with “fingers” of occupancy extending into higher elevations along beaver-dammed streams (see map). These corridors were heavily exploited by hunters and trappers. Beavers were reduced over centuries and were effectively extirpated from South Carolina by the early 1900s. IBWO populations declined concurrently, likely due to direct shooting, logging, elimination of beavers, and then agriculture clearing in the valleys of the upland areas and lowlands, with remnant populations contracting into the sinuous riparian corridors of the Coastal Plain.

National Biodiversity Parks, Inc. (NBP) conducted multi-year point surveys for IBWO in coastal and inland South Carolina, both below and above the Fall Line. Several IB detections and one visual sighting occurred only in the central part of the state, approximately 35 mi south of the Fall Line, within the largest remaining expanse of old-growth bottomland hardwood forest east of the Mississippi River. All detections used methods authorized under federal permit.

In 2023, John Cely discussed several inland records relative to the Fall Line, a geologic and topographic feature often used to approximate the historical IBWO range in South Carolina. To this author’s knowledge, as of 7/12/2026, no specimens have been documented from the Congaree River, despite its entire stretch being below the Fall Line. The Congaree River is formed by the confluence of the Saluda and Broad Rivers. The Saluda basin originates at the Fall Line and once extended farther west. Construction of the Dreher Shoals Dam and creation of Lake Murray between 1927 and 1930 inundated ∼50,000 acres and displaced any IBWOs present. Prior to impoundment, the river was ∼220 ft above sea level and the area was sparsely settled.

Flooding altered hydrology, with backwater effects, a higher water table, reduced flow, and expansion of swamp and palustrine habitats. Any remaining IBWOs should have found forage along the new shoreline, while many hydrophytic trees died as water levels and the water table rose substantially.

Early in the 2020s, reports of one or more IBWOs emerged from a rural area in northwestern South Carolina with numerous large trees and several disjunct 500-acre patches of older second-growth forest within a fragmented matrix of roads, farms, clear-cuts, residences, timber stands, small parks, and wooded streams. The reports were accompanied by several low-quality cell phone images and videos, four or five which were suggestive of an IBWO and female IBWO.

Upon request, we visited the immediate and surrounding area and located the perch trees shown in the videos. We observed bark scaling consistent with, but not diagnostic of, IBWO. The sightings were adjacent to a 700-acre private forest tract with limited seclusion in some seasons.

To assess IBWO status in northwestern South Carolina, we analyzed aerial imagery to identify the largest contiguous, roadless forest blocks and consulted foresters and biologists regarding woodpecker activity, standing dead wood, seclusion, recent fires, and forest DBH. We then conducted point surveys, transects, and bark-scaling inspections across a 50 × 100 mi area.

 
No definitive evidence of IBWO was observed or obtained. Northwestern South Carolina and the Lake Murray region likely do not harbor a hidden IBWO metapopulation, although occasional seasonal or dispersing pairs may transit the area. This is consistent with conclusions of the South Carolina Ivory-billed Woodpecker Working Group (SCIBWWG) and NBP, though we consider the Working Group’s conclusion that breeding does not occur in Congaree National Park (CNP) to be unsupported.



Over seven days, we surveyed a roughly C-shaped route that included the Broad River, multiple sites in Francis Marion and Sumter National Forests including the Long Cane Ranger District, Belfast WMA, The Territories, and several areas near Lake Murray. Bark scaling on pines was extensive and attributable to Pileated Woodpeckers (Dryocopus pileatus); scaling on stressed deciduous trees was minimal.

We also surveyed the upper Edisto River and CNP, with CNP yielding the only suggestive IBWO sign after only a 4-hour hike in. These results indicate abundant Pileated Woodpeckers in northwestern South Carolina and few, if any, IBWOs, though occasional IBWO pine scaling in competition with Pileateds, etc. remains possible.

In summary, IBWO range in South Carolina was roughly constrained by the Fall Line and the inherent ecological implications. However, the pre-contact range was likely slightly larger than most published maps, based on an ecological model in which temperature and humidity are positive predictors of coleopteran biomass per unit area. Greater coleopteran biomass and diversity would be expected to increase IBWO fledging rates. The species likely bred to elevations of at least 202 m in an interdigitated pattern along streams commonly dammed by beavers, which maintained a continuous supply of stressed and standing dead wood that supported pertinent beetle communities and biomass.

Consistent with records emphasized by Tanner and Cely in South Carolina, NBP agrees with Cely (2023) that there is no ecological reason to exclude the Congaree River corridor from 19th-century IBWO range, given its location well below the Fall Line. NBP teams also detected modern IBWOs in CNP on multiple occasions, further supporting historical occupancy of the river corridor.

NBP point surveys and hikes in select northwestern South Carolina sites yielded no IBWO sign. Our data infers but does not confirm the absence of an IBWO metapopulation in northwestern South Carolina. Lake Murray reports had some supporting evidence but only of possible dispersal from presently unknow secluded IB breeding area(s). CNP is an obvious possibility and SCIBWWG (2013) assertions on no breeding there is premature.

More point surveys are needed in SC and elsewhere to produce data on the IB's modern persistence.

Bibliography

1.  "South Carolina Record Maximum Temperatures and Date". South Carolina State Climatology Office. South Carolina Department of Natural Resources. Retrieved 4 February 2010.
2.  "Map of South Carolina Record Maximum Temperatures and Year". South Carolina State Climatology Office. South Carolina Department of Natural Resources. Retrieved 4 February 2010.
3.  "South Carolina Record Minimum Temperatures and Date". South Carolina State Climatology Office. South Carolina Department of Natural Resources. Retrieved 4 February 2010.
4.  "Map of South Carolina Record Minimum Temperatures and Year". South Carolina State Climatology Office. South Carolina Department of Natural Resources. Retrieved 4 February 2010.