Search Efforts for Ivory-billed Woodpecker in South Carolina
Matthew Moskwik, Theresa Thom, Laurel M. Barnhill, Craig Watson,
Jennifer Koches, John Kilgo, Bill Hulslander, Colette Degarady,
and Gary Peters
Southeastern Naturalist, Volume 12, Issue 1 (2013): 73–84
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2013 SOUTHEASTERN NATURALIST 12(1):73–84
Search Efforts for Ivory-billed Woodpecker in South Carolina
Matthew Moskwik1,*, Theresa Thom2, Laurel M. Barnhill3, Craig Watson4,
Jennifer Koches4, John Kilgo5, Bill Hulslander6, Colette Degarady7,
and Gary Peters8
Abstract - Following the reported rediscovery of Campephilus principalis (Ivory-billed
Woodpecker) in Arkansas, we initiated searches in South Carolina in February 2006, with
additional searches in the winter and spring of 2006—2007 and 2007—2008, concentrating
in the Congaree, Santee, and Pee Dee river basins. We accrued a cumulative total
of 8893 survey hours. We found suggestive evidence in the form of visual and acoustic
encounters, but failed to document conclusive evidence. Based on our search results, we
believe it is unlikely that a population of Ivory-billed Woodpeckers persists in Congaree
National Park and found limited evidence for their presence on other public lands in
South Carolina. However, we cannot rule out the possibility that a small, nomadic population
persists in the state.
Campephilus principalis (L.) (Ivory-billed Woodpecker) once occurred
throughout the southeastern United States in mature bottomland hardwood forests
and, according to some accounts, in upland pine and the ecotone between
these habitats (Jackson 2004, Tanner 1942). In the 19th century, its population
began to decline, largely due to habitat destruction that was locally exacerbated
by over-hunting (Jackson 2002, 2004; Tanner 1942; USFWS 2010).
The bird’s range continued contracting through the early part of the 20th century,
and by 1926, many authorities considered the bird extirpated from the
continental United States (Jackson 2002). In the late 1930s, Tanner (1942)
documented the existence of a small population of Ivory-billed Woodpeckers
in Madison Parish, LA and believed that populations existed in the Santee
Swamp of South Carolina and the Suwanee and Big Cypress regions of Florida,
based on habitat conditions and local sightings. Additional populations
may have also existed in the Southeast (Jackson 2004), because Tanner’s surveys
were not exhaustive. Continued habitat destruction and possibly hunting
led to the decline and assumed extinction of these populations, with the last
1University of Texas at Austin, Molecular Cell and Developmental Biology, 1 University
Station–A6700, Austin, TX 78713. 2US Fish and Wildlife Service, Savannah National
Wildlife Refuge Complex, 694 Beech Hill Lane, Hardeeville, SC 29927. 3US Fish and
Wildlife Service, 160 Phillips Laboratory, Athens, GA 30602. 4US Fish and Wildlife
Service, 176 Croghan Spur Road, Suite 200, Charleston, SC 29407. 5Southern Research
Station, USDA Forest Service-Savannah River, PO Box 700, New Ellenton, SC 29809.
6Assateague Island National Seashore, 7206 National Seashore Lane, Berlin, MD 21811.
7The Nature Conservancy, 1417 Stuart Engals Drive, Suite 100, Mt. Pleasant, SC 29464.
8National Wild Turkey Federation, 5303 SC Highway 391, Prosperity, SC 29127. *Corresponding
author - firstname.lastname@example.org.
74 Southeastern Naturalist Vol. 12, No. 1
widely accepted observation of an Ivory-bill Woodpecker in the United States
from the Singer Tract in Louisiana in 1944 (Tanner 1942).
Despite the scientific community’s conclusion that the bird was extirpated
from the United States, unverified sight records continued throughout the latter
part of the 20th century, with reported sightings in several states in its former
range (Gallagher 2005, Steinberg 2008). In 2005, the Cornell Lab of Ornithology
announced the discovery of a single male Ivory-billed Woodpecker from the
Cache River of Arkansas (Fitzpatrick et al. 2005), although this claim has been
challenged (Sibley et al. 2006). Following this announcement, the United States
Fish and Wildlife Service supported search efforts across the historic range of the
Ivory-billed Woodpecker to determine its current status. In South Carolina, work
began in 2005 with the creation of the South Carolina Ivory-billed Woodpecker
Working Group (SCIBWWG), a partnership of 16 federal and state agencies and
private organizations. This working group coordinated the search effort within
The last generally accepted sighting of the bird in South Carolina was in
1938 by Murray and Sanders on Wadmacon Island (Jackson 2002, 2004; Post
and Gauthreaux 1989). Several unverified, but credible sightings of Ivory-billed
Woodpeckers have occurred to the present day, with clusters of sightings occurring
in Congaree National Park, the Wambaw Creek Wilderness, and the Pee Dee
River Basin (SCIBWWG 2006), suggesting that a population could have persisted
into the early 21st century. Thus, the primary objective of our study was to
determine if a population of Ivory-billed Woodpeckers persists in South Carolina
and, if so, to collect conclusive evidence.
Our searches encompassed 3 major river basins in South Carolina, including
the Congaree, Santee, and Pee Dee. Our efforts focused where
concentrations of credible but unverified sightings had occurred (SCIBWWG
2006) and where mature bottomland hardwood forest continuously dominate
the landscape (Fig. 1).
Congaree National Park protects approximately 10,927 ha of forested
floodplains containing internationally significant ecological resources.
The floodplain forest in this park contains the largest intact tract of old-growth
bottomland forest (approximately 4452 ha) in North America (Davis 2003) and
represents one of the last, best examples of an ecosystem that once covered
more than 4 million ha along river floodplains in the southern United States.
Congaree National Park is part of the South Atlantic Coastal Plain Biosphere
Reserve, a Globally Important Bird Area, and a congressionally designated
wilderness. The unique forests and relatively unaltered ecological conditions
are dependent upon the natural seasonal flow regimes in the streams and
floodwaters that enter the park. This floodplain forest is dominated by Taxodium
distichum (L.) Rich. (Bald Cypress), Nyssa aquatica L. (Water Tupelo),
2013 M. Moskwik, et al. 75
Liquidambar styraciflua L. (Sweetgum), Pinus taeda L. (Loblolly Pine), Quercus
spp. (oak), Fraxinus spp. (ash), and Ulmus spp. (elm). Congaree National
Park contains one of the tallest broad-leaved forests in North America, with
the canopy height averaging 40–50 m in old-growth areas (Jones 1997). Over
500 vascular plant species, including more than 80 native species of trees,
have been documented in the Park (Gaddy et al. 2000).
Francis Marion National Forest (FMNF) in Berkeley and Charleston counties
in South Carolina occupies approximately 106,028 ha in the coastal plain of
South Carolina and is one of the most biologically and ecologically diverse forested
landscapes in the Southeast (USDA 1996). The forest boundary is formed
by the Santee River to the north, the Intracoastal Waterway to the southeast,
and Lake Moultrie and Cooper River to the west (USDA 1996). The FMNF is
comprised of several different landforms, ranging from swamps, floodplains,
and stream terraces to side slopes and xeric ridges. The FMNF contains over 30
different natural communities ranging from a dry Pinus palustris Mill. (Longleaf
Pine) and Quercus laevis Walter (Turkey Oak) woodland to clay-based Carolina
Figure 1. Public lands in South Carolina where searches occurred for Ivory-billed Woodpeckers
over 3 field seasons.
76 Southeastern Naturalist Vol. 12, No. 1
bay wetlands (USDA 1996). There are approximately 451 km of perennial
streams and 60,703 ha of palustrine, riverine, lacustrine, and estuarine wetlands
on the FMNF (USDA 1996).
Little Pee Dee Heritage Preserve consists of 4 distinct tracts (Little Pee
Dee, Ward, Tilghman, and Dargan) in Horry and Marion counties. The total
acreage of all 4 tracts is 3350 ha, with the majority in the Dargan and Little
Pee Dee tracts (Dozier and Stowe 1999). Each tract is adjacent to the Little Pee
Dee River, a black-water river system, and contains representative floodplain
forests comprised of Bald Cypress, Water Tupelo, Nyssa biflora Walt. (Swamp
Tupelo), and Acer rubrum L. (Red Maple) that are seasonally inundated by the
river (Dozier and Stowe 1999). The midstory and forest floor are vegetatively
sparse due to long periods of deep flooding (Dozier and Stowe 1999). Each
tract also contains bottomland hardwood forests that were heavily logged in
the 1950s, but today are dominated by a well-developed canopy of Quercus
nigra L. (Water Oak), Quercus lyrata Walter (Overcup Oak), Quercus phellos
L. (Willow Oak), Sweetgum, Carya aquatica (Michx. f.) Nutt. (Water Hickory),
and Loblolly Pine (Dozier and Stowe 1999). Uplands are dominated by
Longleaf Pine on xeric sand ridges with a midstory primarily of Turkey Oak,
Quercus virginiana Small (Live Oak), and Diospyros virginiana L. (Persimmon)
(Dozier and Stowe 1999).
The Marsh Furniture Wildlife Management Area (WMA) comprises 3464
ha in Marion County, SC. The property is bounded to the west by the Great Pee
Dee River, a red-water river system, and includes bottomland hardwood, isolated
freshwater wetlands, and extensive pine and mixed pine-hardwood forests
(SCDNR 2010). The hardwood stands are in the river flood plain, and species
composition includes oak, Carya spp. (hickory), Nyssa spp. (gum), ash, Acer spp.
(maple), and Taxodium spp. (cypress) (SCDNR 2010). Various early successional
hardwoods such as Populus spp. (cottonwood), Salix spp. (willow), Sweetgum,
and Liriodendron spp. (poplar) are prevalent especially within recent hardwood
clearcuts (SCDNR 2010). Pine areas are dominated by plantation and naturally
regenerating Loblolly Pine (SCDNR 2010).
The 10,387-ha Woodbury WMA is managed for pine and hardwood timber
production. The area is bounded by the Great Pee Dee River to the west and
Little Pee Dee River to the east resulting in both black- and red-river floodplain
communities, with similar vegetation to the Little Pee Dee Heritage Preserve
and Marsh Furniture WMA, respectively. Between the river systems are uplands
dominated by Pinus spp. (pine) (SCDNR 2009).
Our search efforts occurred from February to April of 2006 (Year 1), November
2006 to May 2007 (Year 2), and November 2007 to May 2008 (Year
3). Search seasons occurred when the majority of broadleaf trees were leafless,
allowing for better visibility across the floodplain. Our search methods included
2013 M. Moskwik, et al. 77
2 approaches: active ground searches by observers and passive techniques using
autonomous recording units (ARUs).
Active ground searches included “exploratory” and “patch” searches. Observers
were not required to stay within defined areas for “exploratory” searches, but
covered large regions relatively quickly to determine whether an area warranted
a more systematic survey, such as “patch” searching. “Patch” searching was
conducted in regions where observers recorded double knocks or “kent” calls
and large cavities, with measurements consistent with historical Ivory-billed
Woodpecker cavities, were found. In contrast to “exploratory”, “patch” searching
required observers to move within defined areas that averaged 202-ha. Table 1
provides the type of searching conducted in each region.
We conducted “patch” searching in Congaree National Park during all field
seasons and in the FMNF in Year 3. The strategy for “patch” searching varied
slightly for each field season. In Year 1 and 2, two to four observers searched
202-ha patches for at least 3 days (Cooper et al. 2006). In Year 3, we created a
400-m grid within patches for Congaree National Park and the FMNF. The grid
allowed for more systematic surveys. Observers began at a grid point at sunrise
and remained stationary for at least 2 hours. After the stationary watch, observers
freely searched the 400-m x 400-m grid cell located immediately to the east for
approximately 4 hours.
During all search activities, all observers continually watched and listened
for the presence of Ivory-billed Woodpeckers and looked for large cavities and
bark scaling (indicative of woodpecker foraging). When cavities were located,
observers photographed and categorized them based on overall size and shape according
to a scale developed by the Cornell Lab of Ornithology (2007a) (A ≥ 10 x
12 cm, B ≥ 8 x 9 cm, or C ≤ 8 x 9 cm). During Year 3, observers watched 79 “A”
cavities in Congaree National Park and 12 in the FMNF for 90 min each (i.e., 60
min before and 30 min after sunset) for at least 1, and up to 4, evenings. Observers
also noted “tight-bark” scaling, indicative of feeding activity by large-bodied
woodpeckers. “Tight bark” is defined as bark that cannot be pried loose with the
fingertips (Cornell Lab of Ornithology 2007a). If feeding sign qualified as “tight
Table 1. Survey effort for Ivory-billed Woodpeckers in several regions of South Carolina during 3
River basin/region Year Survey type Survey hr
Congaree National Park 2006 Patch 1633
2006–2007 Patch 3839
2007–2008 Patch 2590
Francis Marion National Forest 2006–2007 Exploratory 124
2007–2008 Exploratory/patch 134/221
Woodbury Wildlife Management Area 2006–2007 Exploratory 193
2007–2008 Exploratory 49
Marsh Furniture Wildlife Management Area 2007–2008 Exploratory 31
Little Pee Dee Heritage Preserve 2007–2008 Exploratory 79
78 Southeastern Naturalist Vol. 12, No. 1
bark” scaling, observers used the absence or pattern of small excavations into the
exposed wood layer to categorize it as type “A” or “B”, using the Cornell Lab of
Ornithology (2007a) guidelines.
During the search seasons in all regions, observers broadcast characteristic
sounds of Ivory-billed Woodpeckers, either double knocks or “kent”
calls (Allen and Kellog 1937, Tanner 1942) with the intention of eliciting a
response from a bird. The methods varied slightly each year. Beginning in
Year 1, observers used CD players and small speakers to broadcast “kent” calls
recorded from Ivory-billed Woodpeckers in the Singer Tract, LA (Allen and
Kellogg 1937), along with recorded Campephilus pollens (Bonaparte) (Powerful
Woodpecker) double knocks 2 to 3 times daily. Powerful Woodpecker
double knocks were chosen, because they probably closely resemble those of
an Ivory-billed Woodpecker, of which there are no known recordings. Prior
to beginning a broadcast, observers notified all other observers in the field
via two-way radios. The lack of success, as well as conversations with other
researchers (Martjan Lammertink, Cornell Lab of Ornithology, Ithaca, NY,
pers. comm.), suggested that this method might not be effective at eliciting a
response from a woodpecker. In Year 2, we discontinued the use of recorded
double knocks and “kent” calls. In Year 3, we developed devices to manually
create double knocks (Cornell Lab of Ornithology 2007a), which had the
advantage of broadcasting over larger areas than recordings. A double-knock
session consisted of 7 double knocks spaced 10 sec apart, followed by a 5-min
pause, and then 7 more double knocks spaced 10 sec apart. Double knock sessions
were alternated between observers and conducted every hour on the hour
from sunrise until mid-afternoon for the entire field season.
In addition to observers, we placed autonomous recording units (ARUs) at
locations where past visual or acoustic encounters had been reported. We programmed
ARUs to record for 4 hours beginning at sunrise and 4 hours before
sunset for a total of 8 hours each day. We deployed units for 2-wk periods during
the search season. ARUs were sent to the Cornell Lab of Ornithology for analysis
using automatic signal detection and interactive sound-visualization tools
provided by the XBAT software system. All potential Ivory-billed Woodpecker
detections (i.e., “kent” calls or double knocks) were reviewed by 1 or more birdsound
experts with careful attention to surrounding acoustic context. Potential
vocalizations or double knocks were classified into 4 categories using a ranking
system developed by Rohrbaugh (2006). We deployed 2 ARUs in Year 1, 13 in
Year 2, and 15 in Year 3. We placed all units in Congaree National Park with
the exception of 1 unit in the FMNF in Year 2. In addition, 17 ARUs deployed
in 2004 and 2005 in Congaree National Park for bird and amphibian acoustic
surveys and soundscape monitoring were reviewed for potential Ivory-billed
During all field seasons, we placed time-lapse trail cameras (RECONYXTM
PM35T25) near type “A” and “B” bark scaling and cavities to determine the species
feeding and roosting, respectively. With the exception of 1 camera deployed
on a cavity in the Woodbury WMA, all were deployed in Congaree National Park.
2013 M. Moskwik, et al. 79
For bark scaling, we programmed cameras to record images every 12 sec from
sunrise to sunset. We programmed cameras on cavities to record images every
4 sec for 30 min before and 60 min after sunrise, and 60 min before and 30 min
after sunset. We reviewed all photographs from these deployments for use by
Ivory-billed Woodpeckers. We deployed cameras on 8, 43, and 93 bark-scaled
trees and cavities in Year 1,Year 2, and Year 3, respectively.
From February 2006 to May 2008, we accrued a total of 8893 survey hours
searching 9185 ha in South Carolina. Of this total, 8062 survey hours occurred in
Congaree National Park, 479 survey hours in the FMNF, and 352 survey hours on
public and private land in the Pee Dee River Basin (Table 1). Approximately 6755
ha of Congaree National Park (including all 4452 ha of old growth), 1686 ha of
the FMNF, 377 ha of the Little Pee Dee Heritage Preserve, 179 ha of the Marsh
Furniture WMA, and 188 ha of the Woodbury WMA were searched. Forty-six
observers participated in Year 1, 42 in Year 2, and 36 in Year 3. The majority of
these individuals were trained, unpaid volunteers.
Observers located 83 “A” and 205 “B” cavities in all search regions. In addition,
they recorded 149 trees with “tight bark” scaling; 68 of these categorized
as “A” and 79 as “B” scaling (Table 2). Ninety-one “A” and “B” cavities were
watched by single observers for 90 min at sunset for roosting birds. No Ivorybilled
Woodpeckers were encountered during cavity watches; however, observers
noted a variety of other woodpecker species using the cavities, including Dryocopus
pileatus (L.) (Pileated Woodpecker).
Observers reported several acoustic encounters, the majority in Congaree
National Park. In Year 1, observers reported 5 acoustic encounters. Three of
the encounters were single “kent” calls, 1 was a series of 2 “kent” calls, and 1
included several double knocks heard in series (number unspecified). In Year 2,
observers reported 15 “kent” call encounters, 12 of which were a series of 2 to 12
calls. Additionally, observers reported 13 double-knock encounters, 5 of which
were a series of 2. One of the single double knocks occurred shortly after an observer
completed a double-knock session. In Year 3, observers reported 4 “kent”
call encounters, with 3 to 6 “kent” calls during each encounter. Observers also
reported 13 double-knock encounters, 6 of which were a series of 2 to 5 double
knocks. Additionally, 4 of the double-knock encounters occurred shortly after a
Table 2. Number of “A” and “B” cavities and bark scaling found per region during 3 field seasons
in South Carolina.
Cavity Bark scaling
Region “A” “B” “A” “B”
Congaree National Park 76 189 67 65
Francis Marion National Forest 5 10 1 7
Woodbury Wildlife Management Area 0 3 0 2
Marsh Furniture Wildlife Management Area 2 1 0 1
Little Pee Dee Heritage Preserve 0 2 0 4
80 Southeastern Naturalist Vol. 12, No. 1
double-knock session. Finally, in the FMNF, observers reported 2 double-knock
encounters. In both cases, the observer reported 2 double knocks in series.
In addition to acoustic encounters, a few visual encounters were reported
from Congaree National Park, although all were brief views by single observers.
These visual encounters did not provide enough diagnostic field marks to
completely rule out other species. In Year 1, four observers reported 7 visual
encounters, all of which were brief fly-bys. In Year 2 and 3, single brief visual
encounters were reported.
Trail cameras produced approximately 3 million images over the 3 field
seasons, requiring approximately 850 person hours to review. After close
examination of these images, no Ivory-billed Woodpeckers were noted; however,
Pileated Woodpecker, Picoides pubescens (L.) (Downy Woodpecker), Picoides
villosus (L.) (Hairy Woodpecker), Melanerpes carolinus (L.) (Red-bellied
Woodpecker), Strix varia Barton (Barred Owl), and Sciurus carolinensis Gmelin,
1788 (Eastern Gray Squirrel) were photographed using cavities. These species
in addition to Melanerpes erythrocephalus (L.) (Red-headed Woodpecker), Buteo
lineatus (J.F. Gmelin) (Red-shouldered Hawk), Thryothorus ludovicianus
(Latham) (Carolina Wren), Meleagris gallopavo L. (Wild Turkey), and Turdus
migratorius L. (American Robin) were documented on bark scaling.
ARUs deployed in Congaree National Park recorded several double knocks
and “kent” calls ranked as plausible Ivory-billed Woodpecker using criteria outlined
in Rohrbaugh (2006), with no likely alternative apparent in the context of
the recording (Table 3). Additionally, 1 unit in the FMNF in Year 2 recorded for
113 hours with no recorded Ivory-billed Woodpecker sounds.
Over 3 field seasons in South Carolina, the majority of reported encounters
and recorded events occurred in Congaree National Park. All ARU doubleknock
events were single occurrences, although observers reported double
knocks in series, as well as responses to playback sessions. Unfortunately,
there are no recordings of the observer-reported events. All “kent” calls were
reported by observers, with the exception of 1 event on an ARU in Year 2.
Although many of the encounters were reported by experienced personnel,
a number of unrelated phenomena have been shown to sound similar to
Ivory-billed Woodpecker double knocks and “kent” calls (Cornell Lab of Ornithology
2007b, Rohrbaugh and Rosenberg 2006).
Table 3. Number of units, total recorded time, and type and number of detected sounds on autonomous
recording units (ARUs) for 5 years in Congaree National Park.
Year(s) No. of units No. of recorded hr Single double knock Single “kent” call
2004 5 1114 0 0
2005 12 3493 0 4
2006 2 335 2 0
2006–2007 12 1495 3 1
2007–2008 15 1583 4 0
2013 M. Moskwik, et al. 81
Of the possible alternate explanations for double knocks, it is unlikely that
distant gunshots, duck wing collisions, or vehicles crossing bridges could have
been the origin in Congaree National Park. Hunting is illegal within Park boundaries,
and all reported encounters occurred at least 1.5 km from a road. However,
we cannot completely rule out gunshot sounds, which can travel several kilometers,
and hunting does occur on Congaree’s west boundary. We believe it is also
unlikely, but cannot completely exclude the possibility, that our reported double
knocks originated from duck wing collisions, because observers reported that
they did not see or hear ducks during Ivory-billed Woodpecker encounters. Finally,
we also cannot rule out that the double knocks did not originate from other
woodpeckers, such as Pileated Woodpeckers, which are abundant in the national
park. However, it is unlikely for Pileated Woodpeckers to respond to observerbroadcasted
double knocks or to produce a series of double knocks. Additionally,
it would be unlikely that double knocks from a Pileated Woodpecker would be
independent of other sounds, such as drumming or calling.
Verifying potential Ivory-billed Woodpecker “kent” calls is also problematic.
There are many other possible explanations for “kent” calls, including
creaking and rubbing trees, squirrels, and other bird species (Cornell Lab of
Ornithology 2007b). We were not able to rule out these alternative possibilities,
especially since recordings were not available in most cases.
After 3 field seasons, we do not have photographs or videos of an Ivorybilled
Woodpecker, and all sightings were based on impressions without definite
descriptions of field marks. Overall, our sighting evidence is limited and inconclusive.
This limited sighting evidence in Congaree National Park could be due
to the lack of Ivory-billed Woodpeckers or the difficulty of observing birds in a
We believe two conclusions could be drawn from the search effort in South
Carolina. The first possibility is that Ivory-billed Woodpeckers are extirpated
from Congaree National Park and possibly from South Carolina. We believe that
this is a strong possibility, since there are alternate explanations for the evidence
observed (Cornell Lab of Ornithology 2007b, Rohrbaugh and Rosenberg 2006).
Specifically, the bark scaling could be the result of other foraging woodpecker
species. On a few occasions, observers noted Pileated Woodpeckers creating
“tight bark” scaling. Cavities resembling Ivory-billed Woodpecker cavities could
also have been created by the weathering of small cavities, squirrels, or other
woodpeckers. Additionally, we cannot rule out that the sound and visual evidence
came from sources other than an Ivory-billed Woodpecker. Finally, this conclusion
would agree with recent analyses by Gotelli et al. (2011) and Solow et al.
(2012), which suggest that Ivory-billed Woodpeckers probably went extinct no
later than 1980 or 1988, respectively.
The alternate possibility is that Ivory-billed Woodpeckers persist in South
Carolina, and our search effort was unable to obtain conclusive proof in the
form of a video or photograph. If Ivory-billed Woodpeckers do persist in South
Carolina, we believe that they would have to persist in very low densities, be
highly nomadic, and very elusive. Ivory-billed Woodpeckers by some accounts
82 Southeastern Naturalist Vol. 12, No. 1
were never common and finding one took great effort (Allen and Kellogg 1937,
Tanner 1942); thus, they may have always persisted in low densities. Establishing
that Ivory-billed Woodpeckers are nomadic, moving frequently between
ephemeral sources of food is difficult, because there is little documentation of
this life-history characteristic. However, nomadic behavior has been documented
in several other species of woodpeckers (Block and Brennan 1987, Dixon and
Saab 2010, Pierson et al. 2010, Smith et al. 2000). Thus, it remains possible that
Ivory-billed Woodpeckers frequently shifted their home ranges in response to
food availability, which would make them difficult to locate. Finally, there is
some debate as to how vocal and secretive the species is. Tanner (1942) suggested
that they were highly vocal and not elusive; however, Allen and Kellogg
(1937) suggest that the species was quiet and shy. This contradiction is currently
unresolvable; however, we believe that persistence would require an elusive and
Our efforts cannot completely rule out the possibility that a small, nomadic
population persists in South Carolina, because it is difficult to conclusively prove
the expiration or extinction of a species. However, we believe it is unlikely that a
population of Ivory-billed Woodpeckers persists in Congaree National Park due
to the absence of firm results despite persistent search efforts for 3 years. Additionally,
we found no evidence for their presence on other public lands in the
state, although the search effort was not as intensive in these areas.
This work was made possible through grants and contributions from the US Fish and
Wildlife Service, National Park Service, USDA Forest Service, The Nature Conservancy,
South Carolina Department of Natural Resources, South Carolina Ivory-billed Woodpecker
Working Group, Cornell Lab of Ornithology, and numerous volunteers and staff.
Special thanks to crew members Matt Drury, John Sargent, Gordon Gover, Jeremy Mizel,
James Fuller, John Treasure, Amy Leist, Zach Nelson, Katie Martin, and Brett Hubbard.
Additionally, many thanks go to the Cornell Mobile Team: Martjan Lammertink, Utami
Setiorini, Nathan Banfield, and Chris McCafferty.
Allen, A.A., and P.P. Kellogg. 1937. Recent observations on the Ivory-billed Woodpecker.
Block, W.M., and L.A. Brennan. 1987. Characteristics of Lewis’ Woodpecker habitat on
the Modoc Plateau, California. Western Birds 18:209–212.
Cooper, R.J., R.S. Mordecai, B.J. Mattsson, N.P. Nibbelink, K.W. Stodola, M.J. Conroy,
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a region-wide search for the Ivory-billed Woodpecker with the objective of
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Fitzpatrick, J.W., M. Lammertink, M.D. Luneau, Jr., T.W. Gallagher, B.R. Harrison,
G.M. Sparling, K.V. Rosenberg, R.W. Rohrbaugh, E.C.H. Swarthout, P.H. Wrege,
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