*OURNALOF&IELD/RNITHOLOGY
J. Field Ornithol. 84(3):299–303, 2013
DOI: 10.1111/jofo.12028
Effect of capture frequency on the survival of Piping
Plover chicks
Kelsi L. Hunt,1 Daniel H. Catlin, Joy H. Felio, and James D. Fraser
Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg,
Virginia 24061, USA
Received 4 September 2012; accepted 6 February 2013
ABSTRACT. Evaluating the possible effects of intensive research on species being studied and on the results
of studies is important for both ethical and scientific reasons. We captured, banded, recaptured, and measured
prefledged Piping Plover (Charadrius melodus) chicks during the 2010 breeding season at Lewis and Clark Lake on
the Missouri River in South Dakota. We evaluated the potential for increased mortality related to frequent handling
of chicks with an experiment that compared the survival of chicks handled a single time for banding (N = 48) to
chicks handled repeatedly from hatch to fledge (N = 50). Estimates of daily survival rate (!) for chicks in the two
treatments did not differ (!single-capture = 0.984 ± 0.006, !multiple-capture = 0.985 ± 0.006). Similar to previous studies,
we found little evidence of increased prefledge mortality associated with frequent handling of Piping Plover chicks.
However, because the effects of frequent handling of shorebird chicks may vary among species and other factors
such as habitat quality (e.g., food availability), we suggest that, where possible, researchers include experiments
similar to ours to evaluate possible research impacts, especially when studying threatened and endangered species.
RESUMEN. Efecto de la frecuencia de captura en la sobrevivencia de pichones de
Charadrius melodus
El evaluar los posibles efectos de investigaciones intensivas, en las especies estudiadas, y los resultados de dichos
trabajos son muy importantes por razones tanto cientı́ficas como éticas. Capturamos, medimos y anillamos prevolantones de Charadrius melodius, durante la temporada reproductiva, en el lago Lewis y Clark del rio Missouri en
Dakota del Sur. Evaluamos el potencial de incrementar la mortalidad, relacionada con la frecuencia de manipular
pichones, en un experimento que comparó, la sobrevivencia de pichones que fueron capturados una sola vez, para
ser anillados (N = 48), con pichones repetidamente manipulados desde que nacieron hasta que volaron (N = 50).
No se encontró diferencia en los estimados de la tasa diaria de sobrevivencia (!) para las dos categorı́as (!captura simple
= 0.984 ± 0.006, !captura múltiple = 0.985 ± 0.006). Al igual que en otros estudios, encontramos muy poca evidencia
entre la frecuencia de manipulación e incremento en la mortalidad en estas aves. Sin embargo, debido a que el
efecto de la manipulación de playeros, pudiera variar entre especies y otros factores como la calidad del hábitat (ej.
disponibilidad de alimento), sugerimos, cuando sea posible, que los investigadores incluyan experimentos similares
a los nuestros, para evaluar el posible impacto del estudios, particularmente cuando se esté trabajando con especies
en peligro de extinción.
Key words: Charadrius melodus, live recaptures, Missouri River, program MARK, recapture, research effects
Studies of shorebirds often involve capturing,
banding, and handling chicks (Thomson 1994,
Bart et al. 2001, Grant 2002, Cohen et al. 2006,
Le Fer et al. 2008, Catlin 2009, Sharpe et al.
2009), but few investigators have examined the
possible effect of such activities on the birds or
on the results of their research. For example,
one of the assumptions of mark-recapture is that
the act of marking an animal does not affect
survival (Lebreton et al. 1992). Studies of the
effects of research-related activities on shorebird
chicks have generally revealed that such activities
have no effect on survival. For example, band1
!
C
Corresponding author. Email: [email protected]
ing Semipalmated Sandpiper (Calidris pusilla)
chicks at hatch and subsequently recapturing
chicks 1–2 times before fledging did not affect
survival or mass gain (Bart et al. 2001). Roche
et al. (2010) found that capturing and banding
Piping Plover (Charadrius melodus) chicks 5–
15 d posthatch had no effect on survival to
fledging. Banding and radio-tagging Eurasian
Curlew (Numenius arquata) chicks near hatch
(24–36 h) and the disturbance related to a
recapture interval of 1–3 d had no effect on
their weight gain or survival (Grant 2002). In
contrast, Sharpe et al. (2009) found that radiotagging and frequent handling (recapture every
3 d) of Northern Lapwing (Vanellus vanellus)
chicks led to decreased body condition and
C 2013 Association of Field Ornithologists
2013 The Authors. Journal of Field Ornithology !
299
300
K. L. Hunt et al.
decreased survival of radio-tagged chicks as well
as their untagged broodmates (recapture every
4.5 d).
Given the lack of previous information regarding how frequent handling may affect Piping Plover chicks and the limited number, and
mixed results, of studies where the effect of
research-related activities on shorebird chicks
has been evaluated, our objective was to test
the effect of frequent recaptures on prefledged
Piping Plover chicks. We captured, banded, and
recaptured Piping Plover chicks on the Missouri
River from 2005 to 2011 to obtain estimates of
growth rate and survival to fledging. During the
2010 breeding season, we evaluated the potential
for increased mortality due to frequent handling
of chicks by comparing the survival rates of
chicks handled a single time for banding to
that of chicks handled repeatedly from hatch
to fledge.
METHODS
Study area. We studied Piping Plovers on
two sandbars on Lewis and Clark Lake (hereafter
the Lake), a reservoir on the Missouri River
impounded by the Gavins Point Dam (42◦ 51# N,
97◦ 29# W) (Fig. 1). To restore habitat for Piping
Plovers and Least Terns (Sternula antillarum),
the sandbars were created in 2007 and 2008
(32.95 ha and 58.65 ha, respectively) by the
U.S. Army Corps of Engineers (USACE). These
sandbars were comprised of low unvegetated
mud and sand flats with higher areas of either barren sand or dominated by cottonwood
(Populus spp.) and willow (Salix spp.) saplings.
During the breeding season, herbaceous plants
grew along the shorelines of most sandbars.
Sandbars were located 130–360 m from marsh
habitat and 210–1300 m from the shoreline. In
2010, a maximum of 51 active Piping Plover
nests were located on the larger sandbar and 24
on the smaller sandbar. Possible nest and chick
predators in the study area included raccoons
(Procyon lotor), American mink (Neovison vison),
American Crows (Corvus brachyrhynchos), and
Great Horned Owls (Bubo virginianus; Catlin
et al. 2011a, b).
Prior to hatching, sections of nesting habitat
on the sandbars were randomly assigned as
single-capture and multiple-capture treatment
areas. We designated three single-capture treatment sections (total = 45.05 ha) and two
J. Field Ornithol.
multiple-capture treatment sections (total =
27.75 ha). Other sections of the sandbars were
not included in our experiment, and these areas
served as buffers between treatment groups. We
did not band chicks that hatched in these buffer
areas. The average distance across buffer areas
was 237.5 m (range = 135–405 m), but there
were no physical barriers between treatment
sections.
Chick capture and recapture. Throughout the 2010 chick-rearing period (May–
August), we attempted to capture Piping Plover
chicks starting on hatch day. Chicks that hatched
in multiple-capture treatment sections were subjected to repeated capture attempts (every 2–3
d as per permit restrictions) and measurement
throughout the prefledge (∼25 d) period. The
multiple-capture treatment was similar to methods we used in the previous 5 yr to capture and
measure Piping Plover chicks on the Missouri
River and the Lake (mean captures per chick =
3.6 ± 2.6 [SE]). We tried to avoid capturing
chicks that hatched in single-capture treatment
sections beyond the initial capture and banding.
Instead, we attempted to read the color bands of
these chicks with a spotting scope from distances
between 3 m and 30 m. The designation of
single-capture treatment and multiple-capture
treatment followed the brood to fledging (∼25
d) or death, even if they moved to a different
treatment section after hatching and banding.
We attempted to read color bands prior to
recapture to determine experimental status (i.e.,
single- vs. multiple-capture broods) and to maximize our resighting rate in case chicks evaded
recapture. Single-capture treatment chicks accidentally recaptured were measured and released
with the other chicks.
During chick capture, ≥4 individuals formed
a semicircle around broods, using the shoreline
as a barrier to escape. We approached chicks
slowly and captured them by hand, aided by
light netting suspended from a stick that, when
placed in front of a chick, impeded its movement. When initially captured, chicks received
a unique color band combination consisting of
a Darvic flag and three Darvic color bands. We
used the estimated hatch date from frequent nest
visits (∼2.6-d interval; Catlin et al. 2011a) to
calculate the ages of chicks. We measured mass
(±0.1 g), wing chord (±0.1 mm), and culmen
(±0.1 mm) each time chicks were handled as in
previous years. Although we did not use these
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Piping Plover Chick Survival
301
Fig. 1. Location of our study area on Lewis and Clark Lake, a reservoir on the Missouri River, where we
examined the effect of capture frequency on survival rates of Piping Plover chicks during the 2010 breeding
season.
measurements in our analyses, we collected them
to maintain parity between the methods used
in this experiment and those used in previous
years. The mean time needed to capture, band,
and measure broods was 8.5 ± 2.2 (SD) min at
initial capture and 6.7 ± 2.2 min for subsequent
recaptures.
Estimating survival. Recapture and resighting data were analyzed in Program
MARK (White and Burnham 1999) using the
Cormack–Jolly–Seber live recaptures model. We
tested all combinations of group (g; single- vs.
multiple-capture treatment) and age (a; in days
since hatch), including additive (g + a) and
interactive (g × a) effects on both survival
(!) and recapture rate (p). We used Program
RELEASE to estimate overdispersion (cˆ ) and
used Akaike’s Information criterion adjusted for
small sample size and overdispersion (QAICc )
to evaluate our models (Burnham and Anderson 2002). We present model-averaged estimates and unconditional standard errors for the
survival rates (!) for both groups (Burnham
and Anderson 2002). Values are presented as
means ± SE.
RESULTS
Chicks in the single-capture treatment (N = 48)
were captured less frequently (1.31 ± 0.07 captures, range = 1–3) than chicks in the multiplecapture treatment (2.56 ± 0.17 captures, range
= 1–5, N = 50; ANOVA, F1,96 = 45.4,
P < 0.001). There was no difference in the age
of initial capture of chicks in the single-capture
(1.98 ± 0.39 d, range = 0–10) and multiplecapture (2.10 ± 0.33 d, range = 0–9; F1,96 =
0.1, P = 0.81) treatments.
We found little evidence of differences in
survival of chicks in the single-capture and
multiple-capture treatments based on comparison of information-theoretic model fit criteria (Table 1). The top-ranked survival model
(53.3% of the weight) indicated there was
no difference between treatments. The secondranked model (22.2%) was similar to the first,
with a treatment effect (“group”) added to the
resighting parameter (p), but with little decrease
in deviance associated with the addition (Arnold
2010). The third-ranked model indicated there
was a difference between treatments (17.5% of
the weight). However, the confidence interval
302
K. L. Hunt et al.
J. Field Ornithol.
Table 1. Model ranking results comparing survival rates of single-capture and multiple-capture treatment
Piping Plover chicks on Lewis and Clark Lake on the Missouri River, 2010.
Modela
!(.) p(age)
!(.) p(group + age)
!(group) p(age)
!(group) p(group + age)
!(.) p(.)
!QAICc b,c
0.000
1.749
2.228
4.137
11.708
QAICc wt
0.533
0.222
0.175
0.067
0.002
Likelihood
1.000
0.417
0.328
0.126
0.003
Kd
26
27
27
28
2
Quasi-deviance
196.222
195.538
196.018
195.475
261.227
Group indicates a difference between the single capture sample and the multiple capture sample, and age (in
days) indicates different age-dependent survival or recapture.
b
Akaike’s Information Criterion corrected for small sample bias and overdispersion, cˆ = 2.055.
c
Minimum QAICc = 439.5123. We displayed only models with a !QAICc ≤ 10 and the null model (!(.)
p(.)) for reference.
d
Number of parameters.
a
for the difference between the two groups from
the third-ranked model included 0 ("single-capture =
–0.278, 95% CL –1.477 to 0.921). The modelaveraged estimates of daily survival rate did not
differ between the two treatments (!single-capture =
0.984 ± 0.006, !multiple-capture = 0.985 ± 0.006).
The average resight rate (p) was 0.393 ± 0.050
for single-capture chicks and 0.407 ± 0.050 for
multiple-capture chicks.
On the basis of model-averaged estimates,
66.8 ± 11% of single-capture chicks and 68.4
± 11% of multiple-capture chicks survived to
fledging age (25 d). We observed 54.2% (26 of
48) single-capture chicks after fledging in 2010
and 31.3% (15 of 48) in 2011. For multiplecapture-treatment chicks, we observed 60.0%
(30 of 50) after fledging in 2010 and 44.0% (22
of 50) in 2011.
DISCUSSION
We found no evidence of increased mortality
associated with repeated handling of Piping
Plover chicks. Similarly, Roche et al. (2010)
found no difference in survival rates of banded
and unbanded Piping Plover chicks and noted
increased survival for up to 3 d after capture
and banding occurred. However, chicks in their
study were only captured once for banding (5–
15 d). Survival to fledging in our study was
similar to that for Great Lakes Piping Plovers
(63%, Roche et al. 2010) despite differences
between studies in recapture frequency, further
suggesting that our recapture frequency did not
affect survival.
In contrast, although banding did not affect
survival rates of Northern Lapwings, broods
with a radio-tagged chick that were captured and
handled more often had lower body condition
indices and higher mortality rates than broods
where no chicks were radio-tagged (Sharpe
et al. 2009). In addition, untagged Northern
Lapwing chicks (recapture interval = 4.5 d) in
broods containing one radio-tagged chick were
in poorer condition than their tagged broodmates (recapture interval = 3 d). Sharpe et al.
(2009) speculated that reduced prey availability
coupled with the disturbance of recapture may
have reduced foraging time, leading to food
stress and subsequent reductions in condition
and survival rates of radio-tagged Northern
Lapwing chicks and their broodmates. Thus,
one possible explanation for differences between
our results and those of Sharpe et al. (2009) is
that prey availability in our study area may have
been sufficiently high that Piping Plover chicks
were able to obtain enough food even though
frequent capture and handling may have reduced
the time available for foraging.
Our results suggested that multiple recaptures
did not adversely affect Piping Plover chicks,
but such intensive research is not recommended
unless there is a specific biological or conservation issue and a thorough risk-benefit analysis.
With management partners, we determined that
the benefits of frequently recapturing Piping
Plover chicks (e.g., increased accuracy of prefledging survival estimates and relating foraging
to growth and survival of chicks) warranted the
intensive methods used, particularly given that
we evaluated these risks. Although our results
Vol. 84, No. 3
Piping Plover Chick Survival
can be used to determine tradeoffs between risks
and benefits when planning similar studies, we
suggest that investigators continue to evaluate
their methods where possible, especially when
target species are threatened or endangered.
ACKNOWLEDGMENTS
We thank the U.S. Army Corps of Engineers, the
Virginia Tech Graduate School, and the Department
of Fish and Wildlife Conservation at Virginia Tech for
funding this project. We thank C. Aron, K. Crane, E.
Dowd Stukel, C. Huber, C. Kruse, G. Pavelka, G. Wagner,
W. Werkmeister, S. Wilson, and agency cooperators, the
National Park Service, U.S. Fish and Wildlife Service,
South Dakota Game Fish and Parks, and Nebraska Game
and Parks Commission for logistical support throughout
the project. We thank G. Ritchison, E. Roche, and two
anonymous reviewers for their constructive comments on
this manuscript. We also thank M. Charles, A. Kauth, W.
Lutz, Jr., and J. Schulz for collecting the field data.
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