University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1983 Movements of bald eagles associated with autumn concentrations in Glacier National Park Leonard S. Young The University of Montana Follow this and additional works at: https://scholarworks.umt.edu/etd Let us know how access to this document benefits ou.y Recommended Citation Young, Leonard S., "Movements of bald eagles associated with autumn concentrations in Glacier National Park" (1983). Graduate Student Theses, Dissertations, & Professional Papers. 6693. https://scholarworks.umt.edu/etd/6693 This Thesis is brought to you for free and open access by the Graduate School at ScholarWorks at University of Montana. It has been accepted for inclusion in Graduate Student Theses, Dissertations, & Professional Papers by an authorized administrator of ScholarWorks at University of Montana. For more information, please contact [email protected]. COPYRIGHT ACT OF 1976 Th is is an unpublished manuscript in which copyright sub ­ s is t s . Any further r e p r in t in g of it s contents must be approved BY THE AUTHOR. F'iansfield L ibrary Un iv e r s it y of^FIpj^t a n a D ate : _______ MOVEMENTS OF BALD EAGLES ASSOCIATED WITH AUTUMN CONCENTRATIONS IN GLACIER NATIONAL PARK by Leonard Stephen Young B.A., B.S., University of Maine, 1979 Presented in partial fu lfillm en t of the requirements for the degree of Master of Science UNIVERSITY OF MONTANA 1983 Approved by: Chairman, Board of Examiners Dean, Graduate Scho Date UMI Number: EP37494 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI Dissertation PublishMig UMI EP37494 Published by ProQuest LLO (2013). Copyright In the Dissertation held by the Author. Microform Edition © ProQuest LLO. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQ ^sf ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 -1 3 4 6 v\ Frontispiece.—Bald eagle AF75, captured at Glacier National Park during autumn, shown at her nest on Great Bear Lake, Northwest Territories the following summer (photograph by R. McClelland). 11 ABSTRACT Young, Leonard Stephen, M.S., Winter 1983 W ildlife Biology Movements of bald eagles associated with autumn concentrations in Glacier National Park (102 pp.) Dii rector: B. Riley Me Cl el land Movements of bald eagles (Eat'iaeetus teuoocephatus) associated with autumn concentrations in Glacier National Park were studied during 1979-81. The objectives of the study were to describe movements and habitats used by this group of eagles and to identify a conceptual framework for management of bald eagles and th eir habitats at the regional level. Twenty eagles were captured and equipped with radio transmitters at Glacier National Park during autumns 1979 and 1980. Eagles moved south from Glacier through the Flathead and Swan valleys of northwestern Montana. Three eagles remained in these valleys during winter, but most continued south through eastern Idaho. Wintering areas were documented at American Falls Reservoir on the Snake River, Idaho; the Snake River headwaters region of Wyoming, Idaho, and Utah; the Weber River Valley, Utah; the Rush Valley, Utah; the Snake River near Ontario, Oregon; the Carson Valley, Nevada; and the Klamath Basin, Oregon-California. All wintering areas were within the Intermountain Region. Sightings of additional eagles equipped with colored patagial wing markers at Glacier during autumns 1977-80 fe ll predominantly (93%) within the Intermountain Region and were made most frequently in areas used by transmitter- equipped eagles. In spring, adult eagles followed converging routes from wintering areas to northwestern Montana and continued north along the foothills of the Rocky Mountains through southern Alberta. Near Lesser Slave Lake, Alberta, 2 routes diverged. Some eagles moved north-northeast toward Lake Claire in Wood Buffalo National Park and the east arm of Great Slave Lake, Northwest Territories. Others moved north-northwest toward the west end of Great Slave Lake and Great Bear Lake, N.W.T. Summer ranges were documented at Lake Claire; the Taltson River, N.W.T. ; Great Slave Lake; and Great Bear Lake. The most coherent unit for management of bald eagles and th eir habitats at the regional level appears to be a broad north-south zone, i.e ., a flyway. A flyway system that transcends international boundaries seems to offer the greatest potential for long-term conservation of the species. ii i CONTENTS Page ABSTRACT...................................................................................................................... i 1 i LIST OF TABLES...................................................................................................... vi LIST OF FIGURES.................................................................................................. vii INTRODUCTION .......................................................................................................... 1 ACKNOWLEDGMENTS .................................................................................................. 5 STUDY AREA............................................................................................................... 10 METHODS................................................................................................................... 13 Age and Sex E s tim a tio n........................................................................ 13 Capture and H a n d lin g............................................................................ 14 Wing-Marking ............................................................................................. 19 Telem etry ...................................................................................................... 21 AUTUMN-WINTER MOVEMENTS ................................................................................. 28 Glacier National Park ............................................................................ 28 Northwestern Montana ............................................................................ 30 Eastern Idaho .............................................................................................. 34 Snake River Headwaters ........................................................................ 38 U t a h .............................................................................................................. 40 Western Snake River ............................................... 48 Western Nevada ......................................................................................... 48 Klamath Basin ............................................................................................. 50 WINTER DISTRIBUTION ......................................................................................... 53 SPRING MOVEMENTS .................................................................................................. 58 Utah and I d a h o......................................................................................... 58 O re g o n .......................................................................................................... 60 Montana.......................................................................................................... 62 Southern A l b e r t a ............................................................................ 63 Northern Alberta and Taltson River, N.W.T.................................... 66 Great Slave Lake, N.W.T.......................................................................... 71 Great Bear Lake, N.W.T............................................................................. 71 SUMMER DISTRIBUTION ......................................................................................... 71 DISCUSSION............................................................................................................... 73 Movements...................................................................................................... 73 i V CONTENTS (CONTINUED) Page Communal Roosting ..................................................................................... 79 Food H a b i t s .................................................................................................. 82 Productivity .................................................................................................. 84 Bald Eagle Management ............................................................................. 88 LITERATURE CITED .................................................................................................. 93 LIST OF TABLES Page TABLE 1 Age classes of bald eagles captured at lower McDonald Creek, Glacier National Park during autumns 1977-80 ................................................................................. 18 VI LIST OF FIGURES Page FIGURE 1 Glacier National Park and the upper Flathead Valley, Montana .............................................................................................. 4 2 Lake McDonald and the Continental Divide ...... 11 3 Lower McDonald Creek ................................................................. 12 4 Trap set used to capture bald