IN NORTHERN GULF OF MEXICO TIDAL SALT MARSHES by ANNA JOY JEANETT

149 Pages·2014·0.99 MB·English

BREEDING ECOLOGY OF THE SEASIDE SPARROW (AMMODRAMUS MARITIMUS) IN
NORTHERN GULF OF MEXICO TIDAL SALT MARSHES
by
ANNA JOY JEANETTE LEHMICKE
(Under the Direction of Robert J. Cooper)
ABSTRACT
Tidal salt marshes are critically important habitats that have experienced serious declines
in the United States and still face current and future threats. Marsh birds have been proposed as
potential indicators of tidal marsh integrity, yet the basic biology of many species remains poorly
studied along the coast of the Gulf of Mexico. I examined factors affecting nest-site selection,
nest success, density, and extra-pair paternity of a tidal marsh obligate passerine, the Seaside
Sparrow (Ammodramus maritimus), in two marsh complexes on the Mississippi coast.
Nest placement and survival both appear to be strongly influenced by predation. Nests
were built in areas with more ground cover than random points and better-concealed nests were
more likely to fledge young. These results contrast with those from Atlantic coast tidal marshes,
where nest placement and nest survival are both driven by tidal flooding. Survival was higher for
nests that had closer active neighbors and successful nests were spatially clustered, while
unsuccessful nests were not. More research is needed to determine if Seaside Sparrows are
clustering in areas of low predator potential or if higher densities of birds can more effectively
drive off or warn one another or predators. Elevation and Seaside Sparrow density were
positively related in our study marsh, a result that contrasts with patterns of occupancy at a
broader scale. I suggest that because broad- and fine-scale habitat relationships do not always
agree, both must be considered when predicting species-level responses to potential future
habitat alterations.
I found that extra-pair paternity in my study populations did not seem to have any
adaptive benefit for females and they may be unwilling extra-pair partners. Further research is
needed to confirm and clarify these results, but it is possible that extra-pair paternity represents a
case of sexual conflict in our populations.
While research across a broader area of the northern Gulf of Mexico is still needed, the
results of this study will contribute to a better understanding of the demography and habitat
relationships of the Seaside Sparrow and will increase its usefulness as an indicator for tidal
marsh integrity.

INDEX WORDS: Seaside Sparrow, Ammodramus maritimus, northern Gulf of Mexico, tidal
marsh, nest survival, density, habitat selection, extra-pair paternity
BREEDING ECOLOGY OF THE SEASIDE SPARROW (AMMODRAMUS MARITIMUS) IN
NORTHERN GULF OF MEXICO TIDAL SALT MARSHES

by

ANNA JOY JEANETTE LEHMICKE
B.S., University of Delaware, 2008

A Dissertation Submitted to the Graduate Faculty of The University of Georgia in Partial
Fulfillment of the Requirements for the Degree

DOCTOR OF PHILOSOPHY

ATHENS, GEORGIA
2014
© 2014
Anna Joy Jeanette Lehmicke
All Rights Reserved
BREEDING ECOLOGY OF THE SEASIDE SPARROW (AMMODRAMUS MARITIMUS) IN
NORTHERN GULF OF MEXICO TIDAL SALT MARSHES

by

ANNA JOY JEANETTE LEHMICKE

Major Professor: Robert J. Cooper
Committee: Mark S. Woodrey
C. Joseph Nairn
Michael J. Conroy
Sonia M. Hernandez

Electronic Version Approved:

Maureen Grasso
Dean of the Graduate School
The University of Georgia
May 2014
DEDICATION
This dissertation is dedicated to my parents, Albert and Lorraine Lehmicke, for their unending
interest in and support of whatever I choose to do.

iv
ACKNOWLEDGMENTS
Although the final version of this dissertation will bear only my name, it would never
have gotten to this point without the help and support of many other people. Going
chronologically, I first need to thank my undergraduate ornithology professor, Greg Shriver, for
letting me know about this research opportunity and putting in a good word for me. Thanks to
my (in all but name) co-advisers Bob Cooper and Mark Woodrey for agreeing to take me on and
mentoring me through every step of the process. Thanks also to my other committee members,
Joe Nairn, Sonia Hernandez, and Mike Conroy for their help and suggestions along the way. My
dissertation process involved two states with many outstanding people in each. On the
Mississippi side, I am completely indebted to the Grand Bay National Estuarine Research
Reserve for providing me with housing, a boat, supplies, and logistical support. Special thanks to
Tom Stadler for always patiently fixing any mechanical issues with boats and trucks. Much
credit is due to my field technicians, Laura Duval, Kelly Morris, Jennifer Jetchev, Amy
Densborn, and Claire Randall, for patiently enduring early mornings, endless no-see-ums, and
occasionally intolerable weather. Back in Georgia, my fellow Cooperlabbers were an endless
source of support, ideas, and feedback. Special thanks to Ali Leggett for being a partner and
source of support across state lines. My foray into genetics would not have been possible without
the help and patience of the Nairn Lab. Thanks to Denise Lennon, Bonnie Berry, Brian
Shamblin, Haley Houke, and Billy Kim for their willingness to walk me through every step of
the lab work. The Graduate School, the Warnell School of Forestry and Natural Resources, and
the Gulf Coast Joint Venture all funded my assistantship along the way, and the Georgia
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Ornithological Society provided critical funding for the genetics aspect of this project. On a
personal note, thanks to my parents for their interest in and support of my refusal to enter the real
world. Last and foremost, thanks to Clark, without whom I would be lost. Without his sense of
humor, support, encouragement, and Normal Mondays, I’m not sure how much of my sanity
would still be intact today.
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TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS ...............................................................................................................v
CHAPTER
1 INTRODUCTION AND LITERATURE REVIEW .....................................................1
2 NEST-SITE SELECTION AND NEST SUCCESS OF THE SEASIDE SPARROW
IN NORTHERN GULF OF MEXICO TIDAL MARSH ............................................13
3 DENSITY OF SEASIDE SPARROWS IN THE GRAND BAY NATIONAL
ESTUARINE RESEARCH RESERVE .......................................................................54
4 NEST-LEVEL AND INDIVIDUAL CORRELATES OF EXTRA-PAIR
PATERNITY IN THE SEASIDE SPARROW............................................................94
5 SUMMARY AND CONCLUSIONS ........................................................................133

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CHAPTER 1
INTRODUCTION AND LITERATURE REVIEW
Globally, tidal salt marsh covers approximately 45,000 km2 (Greenberg et al. 2006b), an
area slightly larger than the state of Maryland. The United States contains more salt marsh
habitat than any other country, totaling 16,500 km2, over 95% of which is along the Atlantic and
Gulf coasts. Tidal salt marshes are highly productive ecosystems (Adam 1990) and are important
both ecologically and economically. Ecologically, they play an important role in filtering
pollutants from water (Gersberg et al. 1986), are an essential part of estuarine nutrient cycles
(Welsh 1980), and help protect coastlines from erosion (Broome et al. 1988). Economically, they
act as nurseries for many commercially important species of fish and shellfish (Knieb 1997), and
provide numerous opportunities for those seeking outdoor recreation (Niering and Warren 1980).
For centuries, this ecosystem has been threatened in the United States by human
activities. Over the 200-year period from 1780 to 1980, the contiguous United States lost 53% of
its original wetlands (Dahl 1990). These threats continue even today, with an estimated 1% loss
in tidal salt marsh area between 1998 and 2004 (Stedman and Dahl 2008). In the near future, one
of the greatest threats to tidal salt marsh is predicted to be sea level rise (McFadden et al. 2007).
Because of its limited extent, high economic and ecological importance, and continued
threats, tidal salt marsh health must be closely monitored. Since it is often difficult to monitor the
overall health of an entire ecosystem, managers and researchers may rely on one or a suite of
indicator species as proxies for ecosystem health. For tidal marsh in the United States, the
Seaside Sparrow (SESP; Ammodramus maritimus) is perhaps the strongest candidate for this
1