Sparrows are captured at 12–15 sites each of which is sampled
twice per season from December-April during daytime high
tides that are at least 5.8 feet in amplitude. These large tides
concentrate the birds into high marsh roost sites scattered
throughout the salt marsh. The roost sites vary in size
and are typically dominated by black needlerush (Juncus
roemerianus) and/or sea ox-eye (Borrichia frutescens). Fine
mesh nets called mist nets are placed at one end of the
roost site and the birds are flushed into the nets. A group of
volunteers is needed to successfully and efficiently flush the
birds toward the nets. Once the birds are captured, the
birds are removed from the nets and put into a
cloth bag for transport back to the banding
area. The volunteers then fit each bird
with a uniquely numbered aluminum leg
band, take a series of measurements, and
release the birds into the salt marsh.
Over the last four years, 1,006 birds
of 13 different species have been banded
in the salt marsh. An additional 447 birds
have been recaptured, meaning that they
were captured one or more times after their
original banding date. Banding totals for the
three target species are as follow: 559 seaside sparrows
(336 recaptures), 162 saltmarsh sparrows (66 recaptures), and
214 Nelson’s sparrows (39 recaptures). Over time, markrecapture data can be used to assess population densities, site
fidelity, and survivorship.
Banding data clearly shows that site fidelity for seaside
sparrows is incredibly high because the birds are captured
repeatedly at the same location both within and between
years. Saltmarsh and Nelson’s sparrows also exhibit site
Setting the mist nets.
Flushing the birds.
To a habitat specialist, these species are of high
conservation concern. They occupy a narrow band of habitat
that is confined to the East and Gulf coasts of North America,
areas that are increasingly vulnerable to climate change and
sea level rise. Seaside and saltmarsh sparrows spend their
entire life cycles within the tidal salt marsh, many migrating
back and forth from breeding areas in the Northeast
to wintering areas in the Southeast. The Nelson’s
sparrow is a part-time resident of the salt
marsh during the winter months, with the
exception of one subspecies that uses the
salt marsh year-round. Because these
species are so dependent on the salt
marsh, they are important indicators of
salt marsh health. During the winter of
2011–2012, the Town of Kiawah Island
initiated a project to study and monitor
the marsh sparrows that spend the winter
around Kiawah Island. Information collected
from this study such as population density, age
structure, site fidelity, survivorship, and habitat use is critical
to the long-term conservation of these species.
Marsh Sparrow Banding Study
44
Naturally Kiawah