Beaver Habitat Along Rivers and Reservoirs in Central Montana
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University of Montana ScholarWorks at University of Montana Graduate Student Theses, Dissertations, & Professional Papers Graduate School 1988 Beaver habitat along rivers and reservoirs in central Montana Robin Bown 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 Bown, Robin, "Beaver habitat along rivers and reservoirs in central Montana" (1988). Graduate Student Theses, Dissertations, & Professional Papers. 4658. https://scholarworks.umt.edu/etd/4658 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 COPYRIGHT ACT OF 1976 Th is is an unpublished manuscript in which copyright su b sis ts , A ny further reprinting of its contents must be APPROVED BY THE AUTHOR, Ma n s f ie l d .Library Un iv e r s ity of Montana Date : 198 8 ____ 5?1'37 S7g7b BEAVER HABITAT ALONG RIVERS AND RESERVOIRS IN CENTRAL MONTANA By ROBIN BONN B. S., University of Montana, 1980 Presented in partial fulfillm ent of the requirements for the degree of Master of Science U n iv e rs ity of Montana 1988 Approved by Chairman, Board o f Examiners DeriJn, Graduate School/ /TrLiu.^ It,. Vffff Date UMI Number: EP40122 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. Dissalatien PsibJisMng UMI EP40122 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 Bown, Robin R., M.S., June 1988 Beaver Habitat Along Rivers and Reservoirs in Central Montana (116 p p .) Director: Bart W. O’Gara This study was initiated in 1982 as part of the mitigation studies for a proposed hydroelectric dam in central Montana, with the goal of determ ining the e ffe c ts of ru n -o f-th e -riv e r impoundments on beaver and developing potential mitigation strategies. The study areas were the Missouri River at Carter Ferry, Lake Elwell on the Marias River, and the Marias River below Lake Elwell. At Carter Ferry,, beaver use was associated with islands or backwaters, water depths at 1 m from shore of 1.5 dm or less, adjacent river channels of 70 m or less, non-cliff uplands, or the presence of woody vegetation. On the Marias River, beaver used islands or sites with shrubs. At Lake Elwell, beaver used sites with slopes of 19% or less, non-cliff uplands, or the presence of shrubs. Lodges at Carter Ferry were associated with fla t banks, soil substrates, or nearby shrubs. On the Marias River, beaver built lodges on non-cliff sites with soil substrates or greater than 10% underwater slope. At Lake Elwell, lodges were associated with bank aspects of 90 to 210 degrees, soil underwater substrates, or deep water near shore. Seventy-two percent of the shrub cutting by beaver occurred in the fa ll. Within each size class, beaver cut shrubs as close to the water as available. Willow trees were cut more often than expected while other species, except cottonwood and chokecherry, were cut less often than expected. The cut trees were smaller than average and further from shore than expected. Colony densities on the Missouri River varied from 0.03 to 0.31 per kilometer of shoreline. The Marias River below Lake Elwell varied from 0.10 to 0.23 colonies per kilometer. Lake Elwell averaged 0.18 colonies per shoreline kilometer while the Missouri River reservoirs ranged from no colonies to 0.17 per kilometer. Caches were located on islands more often than expected and steep mainland banks less often than expected. - . Potential mitigation,strategies Include replanting vegetation on fla t or terraced banks; controlling water fluctuations on the entire reservoir or small segments of reservoirs using sub-impoundments; controlling the timing and magnitude of downstream fluctuations; and protecting banks with erosion problems through structures or barrier islan d s. ACKNOWLEDGMENTS As w ith any major p ro je c t, I could not have completed th is thesis without the help of numerous others. A special thanks goes to my major professor, Dr. B. W.'O’Gara, who gave.me the opportunity to prove myself and supported me throughout the study; to Dr. I. J. Ball who managed the finances and co n tract; and to my committee, Dr. Howard Hash of the Montana Department of Fish, W ildlife and Parks, Dr. Donald Potts, and Dr. Andrew Sheldon. My deepest gratitude goes to the volunteers, Kathy Heffley, Laura Gutzwiller, Kris Schofield, Sarah Snyder, Amy Hetrick, Sue^Geske, Nathan Hall, Jamie Jisa, and Mark Wilson, who spent long hours in the cold, heat, mud, and snakes gathering the data. I am deeply in debt to Susan Ball, a fellow graduate student, who provided welcome assistance, support, advice, and friendship throughout the study. The e n tire p ro ject would not have been possible w ithout the efforts of Tom O’Neil, of the Montana Power Company, who envisioned the project, and Montana Power Company, who provided the primary funding. Dr. Dave Patterson provided invaluable assistance with the statistical analyses. Drs. Lee Metzgar and W. Daniel Edge were there when I needed advice. My thanks to Jim Hepner, a pilot who was willing to fly under extreme conditions and on short notice. Without his willingness I could not have completed my cache counts. Jim Mitchell and Frank J _ Feist of the Montana Department of Fish, W ildlife and Parks in Great 'Falls, Montana, provided assistance and advice. Several biologists provided input to the project, including Mike Hi 11 is, Greg Munther, and Rob Hazelwood. I am' grateful to the many landowners, throughout the study areas, who allowed us to work on their land, and especially those who ’adopted’ the entire crew, the Urquharts, Gruels, Romingers, and Salisburys. Thanks also to Stan and Debbie Huhtalah, who befriended us a t T ib er Dam. A special thanks goes to Howard Kirk, who taught me everything I know about beaver trapping, and even gave me some of his special lure. • i ' ' _ i Several groups provided additional funding to complete this project, including the University of Montana Graduate School, Montana Department of Fish, W ildlife and Parks, Western Montana Fish and Game Association, Bertha Morton Scholarship Committee, and Clancy Gordon Environmental Scholarship Committee. Finally, and most importantly, my deepest appreciation to my parents, Robert and Rebecca Bown, who have always encouraged me to reach for the stars and believed in my ability to succeed. iv TABLE OF CONTENtS Page ABSTRACT . i i ACKNOWLEDGMENTS •i i i TABLE OF CONTENTS............................................ v LIST OF TABLES................................... v n LIST OF FIGURES . ...................... ix CHAPTER I . INTRODUCTION AND STUDY AREAS Introduction .......................... 1 Objectives ...................... 4 Study A reas ........................................................................... 4 C a rter Ferry . ....................... 6 (Tiber Dam and Lake Elwell ...... ..................................... 7 > Marias River ............................... 8 Additional A reas ........... .....'............................. 9 I I . BEAVER HABITAT USE M e th o d s ............................................................. 13 Results ...................... 16 Carter Ferry ................. 16 Marias River ............................................................... 21 Tiber Dam and Lake Elwell ................................. 21 D is c u s s io n.............................................................. 24 I I I . BEAVER DENNING ACTIVITY Methods .... ................................ .......... 31 Results .......... ................................... 31 Carter Ferry ................................. 31 Marias R iver ............................................................... 36 Tiber Dam and Lake Elwell . .......................... 39 Discussion ....................................................... 41 IV . SPATIAL AND TEMPORAL USE OF WOODY PLANTS BY BEAVER Methods ................................... ........................................ 47 R e s u l t s ................................................................................... 49 Seasonal Cutting Activity . .......................... 49 Spatial Cutting Activity ....................................... 52 D is c u s s io n............................... 68 Seasonal Cutting Activity ........... 68 Spatial Cutting Activity .... ............................... 68 v V. OENSITY, LOCATION, AND SIZE OF BEAVER COLONIES M e th o d s 4 ■................................. .' 75 Results ...................... 76 Colony Density' . .............................. v 76 Cache Location ............................. 77 Colony Size ................. 77 Discussion ........................................■. ............................. 87 Colony D en sity ...................... ,87 Cache L o c a t i o