Managing Vegetation to Restore Tern Nesting Habitat in the Gulf of Maine Juliet S

View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by ScholarWorks@UMass Amherst University of Massachusetts Amherst ScholarWorks@UMass Amherst Masters Theses 1911 - February 2014 2011 Managing Vegetation to Restore Tern Nesting Habitat in the Gulf of Maine Juliet S. Lamb University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/theses Part of the Natural Resources and Conservation Commons, and the Natural Resources Management and Policy Commons Lamb, Juliet S., "Managing Vegetation to Restore Tern Nesting Habitat in the Gulf of Maine" (2011). Masters Theses 1911 - February 2014. 623. Retrieved from https://scholarworks.umass.edu/theses/623 This thesis is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Masters Theses 1911 - February 2014 by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. MANAGING VEGETATION TO RESTORE TERN NESTING HABITAT IN THE GULF OF MAINE A Thesis Presented By JULIET S. LAMB Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements of the degree of MASTER OF SCIENCE May 2011 Wildlife and Fisheries Conservation MANAGING VEGETATION TO RESTORE TERN NESTING HABITAT IN THE GULF OF MAINE A Thesis Presented By JULIET S. LAMB Approved as to style and content by: _____________________________ Curtice R. Griffin, Chair _____________________________ Paul Sievert, Member _____________________________ Stephen W. Kress, Member ______________________________________ Paul Fisette, Department Head Department of Environmental Conservation DEDICATION This is dedicated to my family—John, Diana, Anneka, and Susanne—who believe in what I do even when they don’t quite know what I’m doing, and help me find the will to keep doing it. ACKNOWLEDGEMENTS First and foremost, I thank Scott Hall and Stephen Kress, who gave me the idea, the means, the venue, and the support that made this project possible. I owe them much of my confidence and skill as a researcher, and thank them for entrusting me with this important work. At the University of Massachusetts Amherst, I am indebted to my advisor, Curt Griffin, and committee member, Paul Sievert, for feedback throughout the project. Several other faculty members, including William Patterson, Brenda McComb, Stephen Herbert, and Randall Prostak, offered advice and answered questions on various aspects of research. Brian Botson of Florida Atlantic University and Jeff Kimmons of the University of Arkansas also contributed ideas for vegetation monitoring techniques. For grant assistance, I am deeply grateful to the Friends of Maine Seabird Islands and the Garden Club of America. National Audubon Society’s Seabird Restoration Project also provided financial and logistical support throughout my fieldwork. During the off-season, I was generously assisted by Robert Houston of the US Fish and Wildlife Service, Brad Allen of the Maine Department of Inland Fisheries and Wildlife, Rose Borzik, Maki Briggs, Scott Hall, Amanda Lightcap, Anthonly Liss, Ayla Liss, Pete Salmonsohn, Susan Schubel, and Ellen Westhaver. During the breeding season, seasonal staff members of the Seabird Restoration Program, particularly Kate Freeman, Lindsey Galland, Joe Giambruno, Grant Humphries, Jen Knight, Alison Kocek, Alcides Morales, Leah Mucciarone, Maggie Lee Post, Yvan Satgé, Lauren Scopel, Emily Wiser, and Elizabeth Zinsser, helped collect data. In collecting artificial turf for the weed barrier portion of my experiment, I received a generous donation of used turf from Pirates’ Cove Miniature Golf in South Yarmouth, iv Massachusetts. Corky Brown of CB Enterprises, Sara Clark, Diana Gaumond, Andrew Magnusson, and Yvan Satgé helped me to assemble and transport the materials. I am thankful to all the colony managers and biologists who responded to the survey portion of my thesis: Brad Allen, Susie Burbidge, Ted d’Eon, Scott Hall, Helen Hays, Dan Hayward, Stéphanie Hennique, Kate Iaquinto, Yann Jacob, Ellen Jedrey, Stephanie Koch, Stephen Kress, Julie McKnight, Paul Morrison, Carolyn Mostello, Reg Newell, Stephen Newton, Ian Nisbet, Richard Potvin, Bob Prescott, Gaëlle Quemmerais-Amice, Felicia Sanders, Susan Schubel, Sara Schweitzer, Jeffrey Spendelow, and Suzanne Treyger. Additional support and contact information was provided by Christine Bogdanowicz, Jessica Bolker, Rosalie Borzik, Andrew Boyne, Tony Diamond, Julie Ellis, Mitch Hartley, Colin MacKinnon, Craig Watson, and Hal Weeks. Yvan Satgé assisted with many aspects of the survey, including designing the electronic submission form, translating the survey into French, and researching and recommending European contacts. On a personal note, I’d like to thank Scott Hall, Diana Gaumond, Anneka Lamb, Lisa Burns, and Yvan Satgé for invaluable support and encouragement during the research and writing processes. v ABSTRACT MANAGING VEGETATION TO RESTORE TERN NESTING HABITAT IN THE GULF OF MAINE MAY 2011 JULIET S. LAMB B.A., HARVARD UNVIERSITY M.S., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Curtice R. Griffin Following catastrophic exploitation throughout the North Atlantic, breeding seabird populations have recently begun to recover thanks to the combined effects of regulatory protection and ongoing restoration and management efforts. As bird populations increase, new challenges emerge, one of which is overgrowth of vegetation that limits the open nesting habitat favored by most tern species. Though colony managers have used a variety of measures to reduce vegetation cover, these techniques have rarely been quantified or compared experimentally. During the summers of 2009 and 2010, I applied two different techniques, controlled burning and artificial weed barriers (muslin fabric in 2009; artificial turf in 2010) to experimental plots on Eastern Egg Rock and Outer Green Island, two near-shore seabird nesting islands in mid-coastal Maine. I then monitored both vegetation regrowth and use by nesting terns to assess the effectiveness of these techniques for opening and maintaining Common Tern nesting habitat during a full breeding season, comparing treated plots to vegetated control plots and existing tern nesting habitat. I found that burned areas did not remain open for the full nesting season, but vi regrew shortly after laying, leading to near-complete nest failure in these plots. Tern nest and fledging success was similar in weed barrier (1.37 chicks/pair) and untreated tern nesting habitat (1.38 chicks/pair) plots. I also tested another technique, replacement of existing vegetation, at a limited scale on Outer Green Island, without success. These three techniques represent only a small fraction of the vegetation management techniques used throughout the North Atlantic region. Through literature review and consultation with North Atlantic colony managers, I collected information on vegetation management on 34 tern nesting islands between 33 and 55° N latitude and developed a summary of different vegetation control techniques used. I identified 14 technique types suitable for use in nesting colonies: i.e., that can be applied before and after (but not during) the nesting period of May-July, that do not cause destructive impacts to the surrounding ecosystem, and that involve materials and labor that can be reasonably transported to inaccessible offshore islands. Of these techniques, 8 created usable tern nesting habitat for a full breeding season. The success of different methods depended heavily on the plant communities and soil types involved, although the most successful techniques required constructing habitat over existing vegetation. In general, vegetation management options were more limited and less successful for elevated, rocky islands than for low, sandy islands. Often, techniques that successfully removed one species or group of species (i.e., perennial grasses) failed due to rapid colonization by other species (i.e., herbaceous annuals). This review of past and ongoing vegetation management techniques used on seabird nesting islands, including their costs, methods for application, and effectiveness, hopefully provides seabird managers a reference when evaluating current and future vegetation management programs. vii PREFACE This thesis contains two chapters, each of which is an independent scientific paper formatted for submission to a peer-reviewed journal. The first chapter details the results of a two-year vegetation management experiment on two seabird islands in the Gulf of Maine. It is formatted for submission to Waterbirds. The second chapter is a review of vegetation management techniques used at seabird colonies throughout the mid-North Atlantic, based on the results of a literature review and a survey of colony managers. This review paper is intended as a tool for managers, helping them to assess what vegetation management techniques may be most appropriate at their seabird colonies. This review article is formatted for submission to a technical or professional publication. When I use the word “we” in describing treatment or monitoring, I refer to work conducted with the assistance of National Audubon Society’s Seabird Restoration Program, primarily Research Coordinator Scott Hall and various staff and interns. viii TABLE OF CONTENTS ACKNOWLEDGEMENTS ........................................................................................................... iv

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