Southeastern Naturalist
G.D. Balkcom, P.R. Garrettson, and R.J. Benedict, Jr.
2014 Vol. 13, No. 3
600
2014 SOUTHEASTERN NATURALIST 13(3):600–606
An Evaluation of June Wood Duck Banding in the Southern
Atlantic Flyway
Gregory D. Balkcom1,*, Pamela R. Garrettson2, and R. Joseph Benedict, Jr.3,4
Abstract - In waterfowl banding studies, the preseason banding period is commonly accepted
as July through September; however, in an effort to increase Aix sponsa (Wood
Duck) banding in the Atlantic Flyway, several state agency biologists have considered
banding Wood Ducks in June. We analyzed existing Wood Duck banding data to determine
if direct band-recovery rates of Wood Ducks banded in June differed from those banded
during July–September. We calculated direct recovery rates by state, month, and year for
1998–2007 at selected states in the Atlantic Flyway. Arcsine-transformed direct bandrecovery
rates differed by month of banding (P = 0.0099; F = 3.973; df = 3, 111) and were
lower in June than in July or August. We suggest that state or federal agencies conducting
Wood Duck banding should spend their time and effort during the traditional banding period
1 July–30 September.
Introduction
There are 3 main assumptions in basic mark-recapture studies: (1) the population
is closed to additions and losses during the project, (2) marks are not lost or
overlooked, and (3) all individuals in the population are equally likely to be captured
in each sample (Skalski and Robson 1992, Williams et al. 2002). To meet
assumptions 1 and 2, researchers often try to mark animals so that the time period
between sampling occasions is relatively brief (e.g., days or weeks; Williams et al.
2002). However in reality, the marking period often extends over months in order
to capture a large enough sample size to produce statistically valid results.
Banding is an important tool for waterfowl management, and results are often
used to help establish harvest regulations (Nichols et al. 2007). Establishing waterfowl
hunting regulations in the US involves cooperation by the US Fish and
Wildlife Service (federal government) and the Flyway Councils that represent the
state governments (Blohm et al. 2006). The Atlantic Flyway Council is a coalition
of states, provinces, and territories that works in conjunction with the respective
federal governments to manage migratory birds and their habitats in eastern North
America and along the Atlantic coast. Harvest regulations for many waterfowl
species are set using a process that includes estimates of annual survival rates
and harvest rates that are derived from banding and recovery data (Nichols et al.
1Georgia Department of Natural Resources, Wildlife Resources Division, Game Management
Section, Fort Valley, GA 31030. 2US Fish and Wildlife Service, Division of Migratory
Bird Management, Laurel, MD 20708. 3Florida Fish and Wildlife Conservation Commission,
Division of Hunting and Game Management, Tallahassee, FL 32311. 4Current address
- Tennessee Wildlife Resources Agency, Division of Wildlife and Forestry, Nashville, TN
37204. *Corresponding author - greg.balkcom@dnr.state.ga.us.
Manuscript Editor: Michael Steinberg
Southeastern Naturalist
601
G.D. Balkcom, P.R. Garrettson, and R.J. Benedict, Jr.
2014 Vol. 13, No. 3
1995, Williams and Johnson 1995). In waterfowl banding studies, the pre-hunting
season (hereafter preseason) banding period is commonly accepted as July–
September (Nichols 1991, Nichols et al. 1983). This period begins when most
ducklings have reached the age of at least 4 weeks and are large enough to hold a
standard-sized leg band, and ends immediately before the hunting season, which
can begin in early October.
To increase the number of Aix sponsa L. (Wood Duck) banded each year in the
Atlantic Flyway, several state agency biologists have considered banding Wood
Ducks in June. In the southern US, Wood Ducks begin nesting in late January or
early February compared to early April in the northern portion of their range (Bellrose
and Holm 1994), and hatching may begin in early to mid-March (Davis et al.
2007); therefore, many young birds are large enough to be captured and banded in
June rather than waiting until July or later. Our findings from a literature review
suggested that the preseason banding period was arbitrarily defined as 1 July–30
September because this period relates to the late summer–early fall pre-hunting
season population (Anderson and Henny 1972). At the summer 2012 meeting of
the Atlantic Flyway Migratory Game Bird Technical Section, the Wood Duck Committee
asked for a review of existing June Wood Duck banding data prior to any
states expending extra effort or funds to capture and band Wood Ducks in June. To
help address that concern, we analyzed Wood Duck banding data and tested the null
hypothesis that direct band-recovery rates of Wood Ducks banded in June did not
differ from direct band-recovery rates of Wood Ducks banded during the traditional
1 July–30 September period.
Methods
For the Atlantic Flyway states, we obtained Wood Duck banding and recovery
data from the US Geological Survey (USGS) Bird Banding Laboratory and summarized
them by state and month for 1998–2007, the most recent 10-year period
of stable regulations. Our query did not include females that were caught in nest
boxes, but did encompass all age and sex classes that were captured and banded
during normal banding operations. Banding data from the USGS Bird Banding
Laboratory are most readily available as summaries by 5-day period (e.g., June
1–5, 6–10, 11–15… and 26+); therefore, we couched appropriate analyses during
these same temporal periods. For states with a substantial number (>300) of June
Wood Duck bandings and that also had comparable banding data from July, August,
and September, we calculated direct band-recovery rates for each state and month
in each of the 10 years. A direct band recovery is defined as a recovery that occurs
during the hunting season immediately following the banding period, whereas an
indirect recovery occurs in a subsequent hunting season. We chose direct bandrecovery
rates as the metric of comparison; we assumed that if Wood Ducks banded
in June died or lost their bands at a higher rate than Wood Ducks banded during
July–September, then the direct band–recovery rate of June-banded Wood Ducks
would be lower than the direct band-recovery rate of Wood Ducks banded during
the traditional preseason period. We converted direct band-recovery rates, which
Southeastern Naturalist
G.D. Balkcom, P.R. Garrettson, and R.J. Benedict, Jr.
2014 Vol. 13, No. 3
602
are expressed as percentages or proportions, with arcsine-square root transformation
prior to analysis to stabilize the variances because in a binomial distribution
the variance is a function of the mean (Ott 1988, Sokal and Rohlf 1981). We used
one-way analysis of variance to test for differences in direct band-recovery rates
by state, month, year of banding, and all interactions. We then pooled data across
states and years to test for differences by month of banding. We used Program
R version 2.15.1 (R Foundation for Statistical Computing, Vienna, Austria) for
analyses. Following the analysis of variance, we used Tukey’s honest significant
difference, Student-Newman-Keuls, and Fisher’s least significant difference procedures
to examine pairwise comparisons to determine any differences among
months (Ott 1988). Of the 3 methods, Tukey’s honest significant difference is the
most conservative in detecting differences, the Student-Newman-Keuls procedure
is moderately conservative, and Fisher’s least significant difference procedure is
the least conservative (Ott 1988). To better understand changes in direct bandrecovery
rates across the entire banding season, we plotted direct band-recovery
rates by 5-day banding period, and fit a quadratic equation to the data. There are
twenty-four 5-day periods between 1 June and 30 September. However, no direct
band recoveries occurred for Wood Ducks banded after 25 September; therefore,
we used 23 periods in the analysis.
Results
Only Florida, North Carolina, and South Carolina had a sufficient number
of bandings during each month from June–September to warrant inclusion in
our analyses (Table 1). Of 120 possible state-month-year banding combinations
(3 states x 4 months x 10 years), banding occurred in 115 of those periods. The direct
band-recovery rate averaged 0.053 (SD = 0.001, n = 25,426, where n = number
of bandings) over the entire time period. Transformed direct band-recovery rates
were not different by state (P = 0.063; F = 2.848; df = 2, 91) or year (P = 0.674;
F = 0.178; df = 1, 91), and there were no significant interactions: month*year
(P = 0.666; F = 0.525; df = 3, 91), month*state (P = 0.767; F = 0.552; df = 6, 91),
Table 1. Number of Wood Ducks banded in June by state in the Atlantic Flyway, 1998–2007.
State Bandings
Delaware 12
Florida 768
Georgia 40
Massachusetts 1
Maryland 56
Maine 29
North Carolina 1290
New York 30
Pennsylvania 5
South Carolina 2114
Virginia 1
Vermont 328
Southeastern Naturalist
603
G.D. Balkcom, P.R. Garrettson, and R.J. Benedict, Jr.
2014 Vol. 13, No. 3
year*state (P = 0.775; F = 0.256; df = 2, 91), month*year*state (P = 0.225; F =
1.395; df = 6, 91); therefore, we pooled data across states and years and found
transformed direct band-recovery rates differed by month of banding (P = 0.00987;
F = 3.973; df = 3, 111). Direct band-recovery rates averaged 0.035 (SD = 0.003,
n = 4172) in June; 0.051 (SD = 0.002, n = 8925) in July; 0.062 (SD = 0.002, n =
9884) in August; and 0.059 (SD = 0.005, n = 2445) in September (Table 2). The
more conservative Tukey’s honest significant difference procedure and the Student-
Newman-Keuls procedure indicated that transformed direct band-recovery rates
from birds banded in June were not different than those from July or September,
but were different than those from August. The Fisher’s least significant difference
procedure indicated that transformed direct band-recovery rates from birds banded
in June were not different than those from September, but were different than those
from July and August. No other month to month comparisons differed. We conducted
another analysis of the direct band-recovery rate by 5-day banding period
and found that a quadratic equation:
direct band-recovery rate = 0.0001572x2 + 0.005248x + 0.0176,
where x = 5-day banding period, fit the data better (P = 0.00055; F = 16.849; df =
1, 20; R2 = 0.7473) than a linear model (R2 = 0.5344, Fig. 1).
Discussion
Our finding of lower recovery rates of Wood Ducks banded in June is in accordance
with LeMaster and Trost (1994), who reported generally lower direct
recovery rates of birds banded early (15 April–30 June) compared to late (1 July–15
September). A possible explanation for the difference in direct recovery rates is a
violation of the assumption of no mortality between banding period and recovery
period. We attribute this putative mortality to two factors: (1) there is a greater
period of time that birds banded early must survive until the beginning of hunting
season, and (2) lower summer survival of birds banded in the South. LeMaster and
Trost (1994) reported noticeably lower summer survival rates for both adult male
and adult female Wood Ducks in southern and southeastern geographic areas than
for northeastern, north-central, and Great Lakes states regions. Davis et al. (2001)
found relatively robust (>90%) survival of brood-rearing females in Alabama and
Mississippi, but an overall duckling survival of only 21–29% (Davis et al. 2007),
Table 2. Direct band-recovery rates of Wood Ducks banded in Florida, North Caroina, and South
Carolina by month, 1998–2007.
Direct Band-Recovery Rate
June July August September
State Mean SD Mean SD Mean SD Mean SD
Florida 0.035 0.007 0.039 0.005 0.049 0.005 0.055 0.009
North Carolina 0.038 0.005 0.047 0.004 0.066 0.003 0.055 0.007
South Carolina 0.033 0.004 0.059 0.004 0.061 0.005 0.069 0.010
Average 0.035 0.003 0.051 0.002 0.062 0.002 0.059 0.005
Southeastern Naturalist
G.D. Balkcom, P.R. Garrettson, and R.J. Benedict, Jr.
2014 Vol. 13, No. 3
604
although duckling survival varied by site-habitat. Predation was an important mortality
factor for ducklings in their study (Davis et al. 2007). Given that our sample
was biased towards the southern US, where we derived our data from Florida,
North Carolina, and South Carolina, and that summer survival of adult Wood Ducks
is lower in southern areas, we believe that June bandings (at least in southern areas)
may violate the assumption of no mortality between banding and recovery periods,
and that results from June-banded birds may not be comparable to results from
birds banded July–September.
Our results also suggest a larger question about the degree to which bandings
even during the traditional July through September preseason period violate the assumption
of zero mortality due to differences in exposure to threats. A bird banded
1 July must survive 92 days prior to the beginning of the hunting season, whereas
if banded 30 September it needs only survive 1 day. We suggest that techniques for
calculating nest survival might be adapted for use with banding data. Specifically,
the number of days between banding and the beginning of the hunting season could
be used as a standardized individual covariate in survival analyses within program
MARK (Nicolai et al. 2006). Such efforts are beyond the scope of this paper, but
large banding and recovery datasets for many species would lend themselves to
those types of analyses.
Another possible explanation for the difference in direct recovery rates would be
the violation of the assumption that leg bands are not lost or overlooked by hunters.
Leg bands typically have high retention rates, and authors may choose to disregard
Figure 1. Direct band-recovery rates of Wood Ducks banded in Florida, North Caroina, and
South Carolina by 5-day banding period, 1998–2007.
Southeastern Naturalist
605
G.D. Balkcom, P.R. Garrettson, and R.J. Benedict, Jr.
2014 Vol. 13, No. 3
band-retention rates in their analysis, especially when considering only direct recoveries
(Krementz et al. 1996). Retention rates for standard aluminum leg bands
are 0.9995 in North American Geese (Zimmerman et al. 2009); retention rates for
plastic leg bands are 0.998 in adult Pacific Brant (Ward et al. 1997), and retention
rates for plasticine-filled leg bands in day-old ducklings are 0.973–0.986 (Blums et
al. 1999). Because of the typically high retention rates and because we are only considering
direct band recoveries in this analysis, we do not believe that band loss was
a factor in explaining the differences in band-recovery rates by month of banding.
We suggest that state or federal agencies that band Wood Ducks, especially in
southern latitudes, should maintain banding efforts during the traditional banding
period 1 July–30 September. We also advocate particular emphasis on banding between
mid-July and mid-September because bands established during that period
have the highest direct recovery rates of the banding periods examined. States
should be aware that Wood Ducks banded in June have lower direct recovery rates,
and data collected from June-banded Wood Ducks should be used with caution.
Future research should be directed towards exploration of potential age and sex
differences as well as determining other factors that lead to lower recovery rates for
June-banded Wood Ducks, especially in southern areas.
Acknowledgments
We would like to thank the Atlantic Flyway Migratory Game Bird Technical Section’s
Wood Duck Committee for posing this question, and the Wildlife Restoration Program
for partial funding of this project. The findings and conclusions in this article are those
of the authors and do not necessarily represent the views of the Georgia Department of
Natural Resources, US Fish and Wildlife Service, or the Florida Fish and Wildlife Conservation
Commission.
Literature Cited
Anderson, D.R., and C.J. Henny. 1972. Population ecology of the Mallard. I. A review of
previous studies and the distribution and migration from breeding areas. Resource Publication
105. US Fish and Wildlife Service, Washington, DC. 166 pp.
Bellrose, F.C., and D. Holm. 1994. Ecology and Management of the Wood Duck. Wildlife
Management Institute. Stackpole Books, Mechanicsburg, PA. 588 pp.
Blohm, R.J., D.E. Sharp, P.I. Padding, R.W. Kokel, and K.D. Richkus. 2006. Integrated
waterfowl management in North America. Pp. 199–203, In G.C. Boere, C.A. Galbraith,
and D.A. Stroud (Eds.). Waterbirds Around the World: A Global Overview of the Conservation,
Management and Research of the World’s Waterbird Flyways. The Stationery
Office, Edinburgh, UK. 960 pp.
Blums, P., J.B. Davis, S.E. Stephens, A. Mednis, and D.M. Richardson. 1999. Evaluation
of a plasticine-filled leg band for day-old ducklings. Journal of Wildlife Management
63:656–663.
Davis, J.B., R.M. Kaminski, B.D. Leopold, and R.R. Cox, Jr. 2001. Survival of female
Wood Ducks during brood rearing in Alabama and Mississippi. Journal of Wildlife
Management 65:738–744.
Davis, J.B., R.R. Cox, R.M. Kaminski, and B.D. Leopold. 2007. Survival of Wood Duck
ducklings and broods in Mississippi and Alabama. Journal of Wildlife Management
71:507–517.
Southeastern Naturalist
G.D. Balkcom, P.R. Garrettson, and R.J. Benedict, Jr.
2014 Vol. 13, No. 3
606
Krementz, D.G., J.E. Hines, and D.F. Caithamer. 1996. Survival and recovery rates of American
Eiders in eastern North America. Journal of Wildlife Management 60:855–862.
LeMaster, E.T., and R.E. Trost. 1994. Summer survival rate estimates of adult Wood Ducks:
Implications for banding programs. Journal of Wildlife Management 58:107–114.
Nichols, J.D. 1991. Science, population ecology, and the management of the American
Black Duck. Journal of Wildlife Management 55:790–890.
Nichols, J.D., K.J. Reinecke, and J.E. Hines. 1983. Factors affecting the distribution of
Mallards wintering in the Mississippi alluvial valley. Auk 100:932–946.
Nichols, J.D., F.A. Johnson, and B.K. Williams. 1995. Managing North American waterfowl
in the face of uncertainty. Annual Review of Ecology and Systematics 26:177–179.
Nichols, J.D., M.C. Runge, F.A. Johnson, and B.K. Williams. 2007. Adaptive harvest management
of North American waterfowl populations: A brief history and future prospects.
Journal of Ornithology 148:343–349.
Nicolai, C.A., J.S. Sedinger, A.D. Afton, and C.D. Ankney. 2006. Using banding date to
control for assumption violations associated with direct recovery rate estimation: An
example using five decades of Lesser Scaup banding data. Oral Presentation, 4th North
American Duck Symposium, Bismarck, ND.
Ott, L. 1988. An Introduction to Statistical Methods and Data Analysis. Third Edition.
PWS-Kent Publishing Company, Boston, MA. 835 pp.
Skalski, J.R., and D.S. Robson. 1992. Techniques for Wildlife Investigations: Design and
Analysis of Capture Data. Academic Press, San Diego, CA. 237 pp.
Sokal, R.R., and F.J. Rohlf. 1981. Biometry: The Principles and Practice of Statistics in Biological
Research. Second Edition. W.H. Freeman and Company, New York, NY. 859 pp.
Ward, D.H., E.A. Rexstad, J.S. Sedinger, M.S. Lindberg, and N.K. Dawe. 1997. Seasonal
and annual survival of adult Pacific Brant. Journal of Wildlife Management 61:773–781.
Williams, B.K., and F.A. Johnson. 1995. Adaptive management and the regulation of waterfowl
harvests. Wildlife Society Bulletin 23:430–436.
Williams, B.K., J.D. Nichols, and M.J. Conroy. 2002. Analysis and Management of Animal
Populations. Academic Press, San Diego, CA. 817 pp.
Zimmerman, G.S., T.J. Moser, W.L. Kendall, P.F. Doherty, Jr., G.C. White, and D.F. Caswell.
2009. Factors influencing reporting and harvest probabilities in North American
geese. Journal of Wildlife Management 73:710–719.