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2013 SOUTHEASTERN NATURALIST 12(1):85–92
Use of Crop Fields and Forest by Wintering American
Emily B. Blackman1,*, Christopher S. DePerno1, Christopher E. Moorman1,
and M. Nils Peterson1
Abstract - During the 1970s–80s, Scolopax minor (American Woodcock) on wintering
grounds in North Carolina generally used bottomland forests diurnally and fed on earthworms
in conventionally tilled soybean fields at night. Researchers surmised the ridges
and furrows in conventionally tilled fields provided Woodcock protection from predators
and winter weather. Since the 1980s, farmers widely adopted no-till practices for soybean
agriculture, and this change in field structure may have altered Woodcock crop field use.
We returned to the same area as previous research and conducted a study of Woodcock
crop field and forest use in a landscape where crop fields are the dominant open-habitat
type. During December 2009–March 2010, we captured and radio-tracked 29 Woodcock.
Every 24 hours, we located each radio-marked Woodcock during diurnal and nocturnal
periods, and verified the habitat type on foot as either crop field or bottomland forest. We
recorded 94% of nocturnal locations in forest, 6% of nocturnal locations in crop fields,
and 100% of diurnal locations in forest. Percent of an individual Woodcock’s nocturnal
locations in crop fields ranged from zero to 44%, with a mean of 6% (± 2% SE). The
adoption of no-till technology and associated reduction in ridge and furrow micro-habitat
available in crop fields may contribute to the low frequency of Woodcock nocturnal field
use. Because Woodcock primarily were relocated in bottomland forests diurnally and
nocturnally, forest stands should be conserved when managing agricultural landscapes.
Since 1968, Scolopax minor Gmelin (American Woodcock; hereafter
“Woodcock”) in the Eastern and Central Management Regions have experienced
a long-term population decline of 0.8% per year, largely attributable to
the loss of early-successional forest habitat (Cooper and Rau 2012, Dessecker
and McAuley 2001). Fire suppression, urban development, reduced timber
harvest, and forest succession following land abandonment have contributed
to the loss of early-successional habitat in the eastern United States (Thompson
and DeGraaf 2001). Declines in early-successional habitat, combined with
high winter mortality relative to summer mortality (Krementz et al. 1994, Pace
2000), make studies exploring Woodcock habitat use on wintering grounds important
for management efforts.
Research across the winter range reported Woodcock using a variety of habitat
types, including forest (Krementz et al. 1995), pastures, croplands, and old
fields (Glasgow 1958), forest openings (Horton and Causey 1979), and fallow
fields and seed tree timber harvests (Berdeen and Krementz 1998). Generally,
1Fisheries, Wildlife, and Conservation Biology Program, Department of Forestry and
Environmental Resources, North Carolina State University, Raleigh, NC 27695. *Corresponding
author - firstname.lastname@example.org.
86 Southeastern Naturalist Vol. 12, No. 1
wintering Woodcock require habitat with sparse ground cover to allow access
to earthworms and facilitate ground movement, and sufficient overhead cover
for concealment from predators (Berry et al. 2006). Stribling and Doerr (1985)
showed that Woodcock in eastern North Carolina used bottomland forests during
the day and conventionally tilled soybean fields at night to feed on earthworms,
but their study was based on observations and did not evaluate the frequency of
Woodcock field use.
Changes in tillage practices in the decades after Stribling and Doerr’s (1985)
research altered field structure and possibly Woodcock use of crop fields (Blackman
et al. 2012). Conventional-till systems in soybean agriculture created ridge
and furrow topography, but no-till agriculture has become a common practice,
and soybean fields often are planted in flat, narrow rows (Heiniger et al. 2002,
Stribling and Doerr 1985). The ridges and furrows in conventional-till systems
likely provided shelter from winter weather and concealment from predators
(Stribling and Doerr 1985). However, no-till soybean fields lack ridges and furrows,
which may have contributed to a change in Woodcock use of fields at night
(Blackman et al. 2012). Therefore, it is important to document current Woodcock
winter habitat use to focus habitat management efforts. Our objective was to
determine the frequency of diurnal and nocturnal Woodcock field and forest use
across the same study area as previous research in an agricultural landscape in
eastern North Carolina (Connors and Doerr 1982, Stamps and Doerr 1976, Stribling
and Doerr 1985).
We worked in the same area as previous Woodcock research in eastern North
Carolina (Connors and Doerr 1982, Stamps and Doerr 1976, Stribling and Doerr
1985). Our study area included crop fields bordering US Highway 264, and mature
mixed bottomland forests south of Lake Mattamuskeet National Wildlife Refuge
near New Holland on the Albemarle-Pamlico Peninsula in Hyde County, NC (35°
26'36.61"N, 76°10'10.46"W; Fig. 1). All crop fields used for Woodcock capture
were bordered on at least one side by forest, and the distance from capture field to
forest never was greater than 200 m. Crop types were no-till soybean planted after
corn, no-till soybean planted after wheat, disked corn, undisked corn with mowed
stalks, winter wheat, and cotton. No-till soybean fields planted after corn retained
the ridge and furrow topography from the previous corn crop, while no-till soybean
fields planted after wheat lacked ridge and furrow topography because disking occurred
before wheat was planted. Similarly, undisked corn fields retained ridge and
furrow topography, while disked corn fields did not. Also, cotton fields had ridge
and furrow topography, but were uncommon in the study area.
Woodcock captures, banding, and radio-transmitter attachment
During December 2009–March 2010, we captured Woodcock in crop fields
at night using halogen bulb headlamps and hand-held fishing nets strung with
2013 E.B. Blackman, C.S. DePerno, C.E. Moorman, and M.N. Peterson 87
mist netting (Connors and Doerr 1982, Reifenberger and Kletzly 1967, Stribling
and Doerr 1985). The hand-held fishing nets were 58.4 cm wide and 55.9
cm long, and net poles were 142.2 cm long. We sexed (Martin 1964) and legbanded
each captured Woodcock with a size-3 USFWS band, and attached a
4.8-g VHF radio-transmitter (Advanced Telemetry Systems, Box 398, Isanti,
MN) to the skin on the back between the wings using livestock ID tag cement
(Nasco, Fort Atkinson, WI; McAuley et al. 1993). We used a 30-cm-long bellyband
to secure the transmitter around the bird’s breast (McAuley et al. 1993).
We retained Woodcock for no longer than 20 minutes. All capture and handling
methods were approved by the Institutional Animal Care and Use Committee at
North Carolina State University (IACUC Protocol # 08-130-O).
Every 24 hours, we tracked each Woodcock during a diurnal and nocturnal
period and verified the location on foot as either crop field or bottomland forest.
In fields, we verified Woodcock locations visually. For forest locations, we
walked to the edge between forest and field habitats to confirm the forest location.
We collected diurnal locations between 1000 and 1600 hours EST and nocturnal
locations between 1900 and 0100 hours EST. We searched for each individual
Figure 1. Study area south of Lake Mattamuskeet in Hyde County, on the Albemarle-
Pamlico Peninsula of eastern North Carolina. Woodcock were captured in crop fields
bordered on at least one side by mature mixed bottomland forest. Woodcock used all
forest habitat depicted and primarily used crops fields bordering US-264, located on the
northern edge of the crop fields. Previous Woodcock research from the 1970s–80s was
conducted in the same study area.
88 Southeastern Naturalist Vol. 12, No. 1
during every diurnal and nocturnal period. Because Woodcock commonly move
at dawn and dusk, we began our day and nighttime locations at least 30 minutes
after dawn and dusk to ensure that Woodcock had time to move between habitat
types (Glasgow 1958). We used a truck-mounted omni-directional whip antenna
to initially locate Woodcock and a directional hand-held H-type antenna to obtain
locations. We took a minimum of three bearings for each Woodcock location.
When a Woodcock remained stationary for more than 48 hours, we determined
the status of the bird on foot (i.e., alive, dead, or lost transmitter). Girard et al.
(2006) suggested the accuracy of habitat use determination decreased when only
one location was recorded per transmitted individual. Therefore, we removed
individuals with one location from our dataset. We calculated the mean percent
of nocturnal locations in crop fields for all transmitted Woodcock.
Between December 2009 and February 2010, we captured 37 (25 males, 12
females) Woodcock in no-till soybean fields planted after corn (n = 21) and
undisked corn fields (n = 16). All capture fields and subsequent field locations
were within 200 m of forested cover types, and primarily in fields bordering
US-264. We censored three birds (2 males; 1 female): one because of death at
the time of capture, one because of predation within 24 hours after capture, and
one because of injuries received during capture and subsequent predation three
days after capture. Radio-tracking began on 15 December 2009 and continued
until 4 March 2010, when all transmitted Woodcock left the study area. Radio
transmitters remained attached to Woodcock for up to three weeks. The number
of locations recorded per Woodcock varied from zero to 30, with an average
of 12 locations per bird. Five individuals (3 males, 2 females) had less than
two locations because they left the study area, lost their transmitters, or their
transmitters failed, and were excluded from the data set (Girard et al. 2006). We
recorded 100% of diurnal locations in forest (228 locations), 94% of nocturnal
locations in forest (179 locations), and 6% of nocturnal locations in undisked
corn or no-till soybean fields planted after corn (12 locations) (Table 1).
Woodcock were relocated in forest patches north and south of crop fields and
always were relocated within 2500 m of their capture field. For the 29 individual
Woodcock, the mean percent of nocturnal locations in crop fields was 6%
(± 2% SE) with a range of zero to 44% (Table 1).
Radio marked Woodcock were caught in no-till soybean fields planted after
corn and undisked corn fields, and primarily were relocated in mature bottomland
forest. Research from across the wintering range demonstrated diurnal
and nocturnal Woodcock use of mature forested habitats with nocturnal use of
“open” habitats (e.g., seed-tree harvest areas and fallow old fields [Berdeen and
Krementz 1998], pastures [Glasgow 1958], or regenerating clearcuts [Krementz
et al. 1995]). Diurnal Woodcock use of forested habitat is much greater than use
2013 E.B. Blackman, C.S. DePerno, C.E. Moorman, and M.N. Peterson 89
of open habitats (Horton and Causey 1979, Krementz and Pendleton 1994, Krementz
et al. 1995). However, nocturnal use of open-habitat types other than crop
fields can be high. For example, two studies reported 44% and 13% of nocturnal
Woodcock locations in forest openings in central Alabama, and coastal Georgia
and Virginia, respectively (Horton and Causey 1979, Krementz et al. 1995).
Although nocturnal use of crop fields and other open-habitat types varies geographically,
there is greater use of fields greater than 5 ha and of openings with
overhead cover and bare ground to reduce predation risk and facilitate earthworm
foraging (Krementz 2000).
The quality of protective cover available in open habitats may influence
the frequency of nocturnal Woodcock use. In the Georgia Piedmont, greater
nocturnal location rates for Woodcock in seed-tree harvest areas (36%) than in
fallow fields (12%) and hay fields (1%) could be partially explained by greater
foliage volume in timber harvests and the associated protection from predators
(Berdeen and Krementz 1998). Similarly, we recorded greater Woodcock use of
Table 1. Number of diurnal (D) and nocturnal (N) locations per Woodcock in crop fields and bottomland
forest, Hyde County, North Carolina, December 2009–March 2010. No diurnal locations
were in fields.
Woodcock D Forest N Forest N Field % crop field N locations
1 4 2 0 0
2 2 3 0 0
3 3 1 0 0
4 1 3 0 0
5 0 3 1 25
6 2 2 0 0
7 6 2 0 0
8 14 8 0 0
9 2 1 0 0
10 12 5 4 44
11 14 9 0 0
12 13 10 0 0
13 6 1 0 0
14 14 14 0 0
15 10 4 1 20
16 8 4 0 0
17 9 4 3 43
18 10 8 0 0
19 6 7 2 22
20 13 12 0 0
21 7 8 0 0
22 9 10 1 9
23 14 11 0 0
24 10 10 0 0
25 15 15 0 0
26 4 4 0 0
27 7 6 0 0
28 7 7 0 0
29 6 5 0 0
Total 228 179 12
90 Southeastern Naturalist Vol. 12, No. 1
fields with ridge and furrow cover than other field types with no cover (Blackman
et al. 2012). The limited overhead cover in crop fields relative to other
open-habitat types may explain why we documented infrequent Woodcock use
of crop fields compared to greater use rates reported from studies in other openhabitat
Additionally, relatively recent changes in tillage practices and associated
reductions in cover may have decreased Woodcock use of crop fields. Prior
research in our study area reported nocturnal Woodcock use of conventionally
tilled soybean fields, where ridge and furrow topography likely provided
Woodcock with protection from winter weather and concealment from predators
(Connors and Doerr 1982, Stribling and Doerr 1985). However, over the
past 30 years, farmers have adopted no-till practices for soybean planting,
thereby reducing the amount of ridge and furrow topography in the landscape
(Heiniger et al. 2002, Stribling and Doerr 1985). For example, during our study,
ridges and furrows (i.e., cover) were present in no-till soybean fields planted
after corn and in undisked corn fields. However, 74% of no-till soybean fields
were planted after wheat and lacked ridge and furrow topography because disking
occurred before the wheat was planted. Also, infrequent use of crop fields
cannot be explained by limited food resources because all soybean fields,
regardless of tillage practice, contained high food abundance in the form of
earthworms (Blackman et al. 2012). In fact, no-till agriculture leaves soil communities
with greater numbers of earthworms than in tilled fields (Edwards and
Lofty 1982, Smith et al. 2008).
Although trap shyness and weather conditions can influence Woodcock
habitat use, they probably were not determinants of habitat use in our study.
Woodcock in the Alabama Piedmont did not return to their capture field regularly
(Horton and Causey 1979), but other Woodcock telemetry studies did not detect
altered behavior attributable to capture (e.g., Krementz et al. 1995, Myatt and
Krementz 2007). Woodcock in southern Louisiana were more active on nights
with a new moon and warm temperatures than during nights with bright, cold
conditions (Glasgow 1958), and birds in central Massachusetts made relatively
brief visits to fields on cold, frosty nights when compared to nights with milder
weather (Sheldon 1967). However, in our study, transmittered individuals rarely
used crop fields on either warm or cold nights, so weather likely did not influence
our estimates of field use. Although we did not observe temporal variation in field
use, Berdeen and Krementz (1998) noted that Woodcock use of fields decreased
as winter progressed.
Although we documented high use of forest, crop fields appear important for
some Woodcock. Soybean fields had higher earthworm abundance than other
field types, and fields with cover (i.e., ridge and furrow topography) likely provided
thermal protection and concealment from predators (Blackman et al. 2012).
Additionally, Krementz et al. (1995) suggested fallow fields provide important
roosting, courtship, and feeding sites for Woodcock although they are used less
than other habitat types. However, the benefits Woodcock gain from crop fields
compared to forest deserve further attention. Future research should examine
2013 E.B. Blackman, C.S. DePerno, C.E. Moorman, and M.N. Peterson 91
Woodcock nocturnal winter use of forest and should compare earthworm
abundance between crop fields and forested areas used by Woodcock. If forest
earthworm abundance is comparable to earthworm abundance in crop fields, the
combination of equitable food resources and better cover resources in forests
could explain greater location rates in forests than in crop fields. Because the
majority of Woodcock locations were in forested areas, Woodcock habitat management
should include conservation of forest stands in agricultural landscapes
to provide overwintering foraging and roosting sites.
We thank C. Shake, C. Diggins, and J. Stocking for assisting with field research. We
thank J. Connors, K. and B. Davis, B. Desjardins, P. Doerr, J. Gerwin, M. Gibbs, R. Heiniger,
D. Krementz, R. Lancia, D. McAuley, T. Simons, and C. Sorenson for providing
technical assistance on various aspects of the project. Also, we are grateful to all the landowners
who allowed access to their property. Funding for this project was provided by
the US Fish and Wildlife Service Webless Migratory Game Bird Research Program and the
Fisheries, Wildlife, and Conservation Biology Program at North Carolina State University.
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