it would furnish him with food, or shelter, or weapons, or tools, or ornaments, ...... brachyrhynchos), red-tail hawk (Buteo jamacensis), immature bald eagle, osprey .... and laying season of the adults at suburban nest sites especially in 1999.
ECOLOGY OF BALD EAGLES DURING THE POSTFLEDING PERIOD AT RURAL AND SUBURBAN NEST SITES IN SOUTHWEST FLORIDA
Dorothy E. Tinkler
Thesis submitted to the College of Agriculture, Forestry and Consumer Sciences at West Virginia University in partial fulfillment of the requirements for the degree of
Master of Science in Wildlife and Fisheries Science
Petra Bohall Wood, Ph.D., Chair John W. Edwards, Ph.D. Division of Forestry
Charles B. Yuill, M.L.A. Division of Resource Management
Morgantown, WV 2000 Keywords: Bald Eagle, Florida, disturbance, habitat, postfledging
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ABSTRACT Ecology of Bald Eagles During the Post-Fledging Period at Rural and Suburban Nest Sites in Southwest Florida Dorothy E. Tinkler In this study, I examined aspects of fledgling and adult behavior at the nest site. Approximately 90% of the observations placed the fledgling bald eagles within the 456m secondary buffer zone. The fledglings centered their activity in the lowest disturbance levels possible. Fledglings were observed most frequently in the nest, on the ground, or perched in a pine tree. For 92% of the intensively observed individuals, 100% of the 50% core use area occurred within the primary buffer zone. Percent overlap of the 95% core use area with the secondary buffer zone was significantly different between suburban and rural fledglings in 1999, with 46% overlap for rural fledglings and 2.6% for suburban fledglings. Prey delivery and adult attentiveness to the fledgling and nest did not differ between rural and suburban nests. Fledglings departed from the nest sites at approximately the same age across years and site developments.
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Dedication To my parents: To my Dad for being my exploring companion and to my Mother for my independence. Thanks for all your love.
The first man of science was he who looked into a thing, not to learn whether it would furnish him with food, or shelter, or weapons, or tools, or ornaments, or play-withs, but who sought to know it for the gratification of knowing. - Samuel Taylor Coleridge
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ACKNOWLEDGEMENTS There are many people who contributed to the success of this research and I am very grateful to all of them. I would especially like to thank my graduate advisor, Dr. Petra Bohall Wood. I appreciate the opportunity she gave me to study the bald eagle in Florida. I am also grateful for the patience and support Petra gave me during the writing of this thesis. Even though I was one of many I appreciate the open door and the thoughtful discussions about my project, not to mention Ogden and La Paz! I would also like to thank my committee members, Dr. John Edwards and Charlie Yuill for their thoughtful contributions to my study and their reviews of my thesis. I was supported financially by the Florida Fish and Wildlife Conservation Commission. Brian Milsap, Tim Breen, Laura Phillips, Nancy Douglass, and Keith Singleton gave me considerable support while I was in Florida keeping me provided with maps, updates on locations, and Federal Express emergency packages. I really appreciate their willingness to keep me supplied with what I needed to complete my surveys while in Florida. I would like to thank my fellow graduate students for discussions, commiseration, parties, and friendship: Clif and Debbie Tipton, Katie Weakland, Rebecca and Brian Smith, Kim Bjorgo, Jason Freund, Nikki and Steven Castleberry, Ann and Jerry Steketee, Jim Hakala, Mike Kaller, Jon McCloskey, Karen Sacilotto, Bill Warnick, Jon Zuck and Gary Williams. I know that I was really blessed to be working with such a stellar group. Cheers to Mike Strager who helped me out of a GIS quandry several times,
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and acted liked it was one of the most interesting things he had done in a while. I also would like to note Janine Ostergren and Becky Nestor for cheerfulness, moral support, and conversations. I appreciate both of you for your willingness to help straighten the path in this academic world, and doing it with such cheerfulness and ease. Thanks to my family for just being there, and letting me know they thought I was doing something worthwhile. Thank you especially Uncle Stanley, for providing me with the imprimatur on my statistical forays and all the answers to my statistical questions and to my Aunt Betty for making me part of the Morgantown branch of the family. I couldn’t have asked for a sweeter, more loving response to my being here. To all the friends I have met along the way, Donna, Anne, Regina, Cheri, Theresa, Gary, Cathy, and others, thank you for e-mails, line dancing, trips to the zoo, prayers and phone calls.
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TABLE OF CONTENTS INTRODUCTION............................................................................................ 1 OBJECTIVES................................................................................................. 4 STUDY AREA ................................................................................................ 4 METHODS ..................................................................................................... 6 BANDING AND RADIO-TAGGING PROCEDURES .................................................. 6 INTENSIVE NEST OBSERVATIONS .................................................................... 8 EXTENSIVE RADIO TRACKING DATA............................................................... 10 STATISTICAL ANALYSIS ................................................................................ 11 DISTANCE FROM THE NEST ........................................................................ 11 DISTURBANCE AND VEGETATION COVER ..................................................... 11 CENTER OF ACTIVITY ................................................................................. 13 CORE USE AREAS ..................................................................................... 13 PREY DELIVERY ........................................................................................ 14 ADULT ATTENTIVENESS TO THE NEST AND FLEDGLINGS ............................... 14 BEHAVIOR PATTERNS AND PERCH TYPES .................................................... 15 DEPARTURE OF FLEDGLINGS FROM NEST SITE ............................................ 15 RESULTS..................................................................................................... 16 DISTANCE FROM THE NEST ........................................................................... 16 DISTURBANCE AND VEGETATION COVER........................................................ 18 CENTER OF ACTIVITY ................................................................................... 20 CORE USE AREAS ....................................................................................... 21 PREY DELIVERY .......................................................................................... 22 ADULT ATTENTIVENESS TO THE NEST AND FLEDGLINGS .................................. 23 BEHAVIOR PATTERNS AND PERCH TYPES ...................................................... 24 ASSOCIATIONS/INTERACTIONS ...................................................................... 26 DEPARTURE OF FLEDGLINGS FROM NEST SITE ............................................... 27 DISCUSSION............................................................................................... 27 MANAGEMENT RECOMMENDATIONS ..................................................... 32 LITERATURE CITED ................................................................................... 34 TABLES ....................................................................................................... 38 FIGURES ..................................................................................................... 57 APPENDIX ................................................................................................... 68
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LIST OF TABLES Table Page 1. Year, nest ID, rural/suburban designation, and site description of each bald eagle nest intensively observed in southwest Florida during 1998-1999……………………………………………………………………… 38 2. Vegetation and disturbance types identified from aerial photographs of bald eagle nests intensively observed in southwest Florida during 1998-1999………………………………………………………………………
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3. Mean distance (m) from nest for rural (n=4) and suburban (n=8) intensively observed bald eagle fledglings at each week of age in southwest Florida during 1998-1999………………………………………...
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4. Mean distance (m) from nest for rural (n=15) and suburban (n=13) bald eagle fledglings at each week of age observed on overflights in southwest Florida during 1998-1999………………………………………...
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5. Chi square goodness of fit value for use versus availability and corresponding P values for each nest within primary and secondary buffer zones at bald eagle nests in southwest Florida during 1998-1999.
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6. Chi-square goodness of fit test confidence interval results for 8 suburban bald eagle fledglings in southwest Florida during 1998-1999..
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7. Chi-square goodness of fit test confidence interval results for 8 suburban bald eagle fledglings in southwest Florida during 1998-1999… 44 8. Chi-square goodness of fit test confidence interval results for 4 rural bald eagle fledglings in southwest Florida during 1998-1999……………
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9. F and P values for Johnson method hypothesis 1: the relative selections for all disturbance or vegetation types are equal at rural (n=4)and suburban (n=8) bald eagle nest sites in southwest Florida during 1998-1999……………………………………………………………… 46 10. Ranking using Waller-Duncan procedure for Johnson method hypothesis 2 with a K ratio of 100 within the primary buffer zone at suburban nests during 1998-1999 in southwest Florida ………………….
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11. Percent of time rural and suburban bald eagle fledglings perched within and outside the combined primary and secondary protection zone in each disturbance/vegetation cover combination during 1998 and 1999 in southwest Florida…………………………………………………….
47
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12. Percent of the 50% and 95% core use area overlapping each of the bald eagle buffer zones in southwest Florida during 1998-1999…………
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13. Average number of prey deliveries per hour of observation by age to bald eagle fledglings in southwest Florida during 1998-1999 …………
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14. Percent of prey deliveries during each time period at rural and suburban bald eagle nests in southwest Florida during 1998-1999……... 49 15. Percent of observations the intensively observed bald eagle fledglings used 11 perch types during intensive observations and 5 perch types during overflights in southwest Florida 1998-1999………….. 50 16. Percent of observations for each age for each perch type that had a statistically different amount of use between ages (weeks) of bald eagle fledglings in southwest Florida during 1998-1999………………………….
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17. Percent of observations bald eagles fledglings engaged in 11 behaviors during intensive observation and during overflights in southwest Florida 1998-1999………………………………………………… 52 18. Bald eagle nest tree, perch tree height and diameter at breast height in three major nesting regions in southwest Florida during 19981999. Except where noted, all perches were located in living or dead pine trees……………………………………………………………………….
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19. Interactions observed for fledgling bald eagles at 13 nests in southwest Florida during 1998-1999………………………………………...
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20. Nest number, radio frequency of transmitter, date fledgling was 8 weeks old, date of dispersal, and estimated age of dispersal for bald eagle fledglings in southwest Florida 1998-1999…………………………..
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21. Average age of dispersal and standard error for rural and suburban fledgling in southwest Florida 1998-1999…………………………………... 56
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