MIGRATION AND WINTERING ECOLOGY OF THE ALEUTIAN CANADA GOOSE by Dennis W. Woolington A Thesis Presented to The Faculty of Humboldt State University In Partial Fulfillment of the Requirements for the Degree Master of Science June, 1980 MIGRATION AND WINTERING ECOLOGY OF THE ALEUTIAN CANADA GOOSE by Dennis W. Woolington Approved by the Master's Thesis Committee Paul F. Springer, Chairman Stanley W. Harks Natural Resources Graduate Program Approved by the Dean of Graduate StudiesAlba Alba M. Gillespie ABSTRACT A study to determine the migration and wintering ground distri­ bution, ecology, and population status of the endangered Aleutian Canada goose (Branta canadensis leucopareia) was conducted from October 1975 to May 1978. Field investigations extended from the western Aleutian Islands, Alaska, to the. Central Valley of California. Prior to and during the study, 536 Aleutian geese were banded to document movement and survival. It was determined that the geese use traditional migration and wintering areas away from Alaska, returning to virtually the same fields annually. During September, Aleutian Canada geese migrate along the Aleutian Island chain from Buldir Island near the western end to the easternmost island of Unimak and then apparently shift southeast on a transoceanic flight. The geese arrive in California in early October; some stop near Crescent City, but most birds continue to the Sacramento Valley where over 95 percent of the population uses a small agricultural area in the Butte Sink. From mid-November to early December the geese move southward via the Sacramento-San Joaquin River Delta to the grass­ lands of the upper San Joaquin Valley. Most of the birds are present as a single flock near Modesto from at least late December to early February. They begin shifting southward to an area near Los Banos in mid-January, and some are present until mid-March. Aleutian geese start moving northward to the Crescent City staging grounds as early as mid- January, with most of the birds arriving during March. They peak in number there in late March and early April when nearly the entire known iv population is present. In mid-April, geese begin to leave Crescent City to the breeding grounds, and by late April or early May all have left. Although a few Aleutian Canada geese have been reported near the mouth of the Columbia River, Washington, most apparently make a transoceanic flight to the eastern Aleutians. There, they continue westward to Buldir where they have been seen as early as the first week of May. During the study, hunting and avian cholera were found to be the main sources of winter mortality. Closure on Canada goose hunting en­ acted in three areas of California at the onset of the study has reduced mortality from an estimated preclosure rate of 22.5 percent annually to approximately 11.5 percent during winters 1975-76 and 1976-77. This winter mortality may comprise the majority of the annual loss. The spring population increased 45.6 percent, from 790 in April 1975 to 1150 in March 1977. Management needs on the migration and wintering grounds include continuation of protection of the geese through hunting closures and maintenance of suitable habitat conditions on their major use areas. ACKNOWLEDGEMENTS This study was funded by the U. S. Fish and Wildlife Service through a contract with Humboldt State University. Funds, equipment, and vehicles were provided by the U. S. Fish and Wildlife Service through the Endangered Species and Migratory Bird Programs. I would like to thank all the members of my committee for their time and assistance. Committee chairman and study supervisor Dr. Paul F. Springer of the Wildlife Research Field Station, U. S. Fish and Wild­ life Service, provided support, encouragement, and field assistance throughout both the data collection and thesis preparation phases of this study. Dr. Stanley W. Harris and Dr. John 0. Sawyer of Humboldt State University critically reviewed this thesis and suggested revisions that have been incorporated. Because of the large number of people from Alaska to California who also contributed to this study, it would be impractical to individu­ ally thank everyone involved. Personnel of the U. S. Fish and Wildlife Service, California Department of Fish and Game, British Columbia Fish and Wildlife Branch, and Canadian Wildlife Service as well as private individuals including naturalists, sportsmen, landowners, and university students helped conduct observations and provided other assistance. I wish to thank all of these people as a group. A special debt of gratitude is owed to biologist W. E. "Bud" Rienecker and wardens Jack Rhea and the late Leon H. Nelson of the California Department of Fish and Game and law enforcement agents Wallace B. Smith and Alva E. Weinrich of the U. S. Fish and Wildlife Service for vi field assistance. Employed and volunteer workers who conducted observa­ tions while I was in other areas include William E. Rodstrom, Gary Lester, Tom Greener, Ernest P. Camillari, William G. Henry, Jack T. Loris, Randy March, and Larry R. Kludt. During the study, housing was provided by the Gray Lodge, Los Banos, and Grizzly Island Wildlife Areas and the Izembek, San Luis, and Willapa National Wildlife Refuges. I wouLd like to thank the respective state and federal property managers John R. Cowan, Jerome C. Cawthorn, Clyde S. Edon, John E. Sarvis, Leon A. Littlefield, and Joseph W. Welch for this privilege and their hospitality. The late Roger Wilbur, owner of the West Butte Farms and Butte Creek Farms; Paul L. Davies, owner of the Faith Ranch; C. E. Nemethi, owner of the Nemethi Land and Cattle Company; Henry and Robert Westbrook, owners of the Reservation Ranch; and Loren C. Bliss, owner of the L. C. Bliss and Sons Livestock Company, kindly allowed access to their proper­ ties. Janice R. Chandler, secretary at the Wildlife Research Field Station, typed the thesis drafts. Finally, I would like to thank G. Vernon Byrd for first intro­ ducing me to the world of the Aleutian Canada goose. TABLE OF CONTENTS Page ABSTRACT iii ACKNOWLEDGEMENTS LIST OF TABLES xi LIST OF FIGURES xiv INTRODUCTION 1 Overview 1 Historical Perspective 2 STUDY AREA 9 Description 9 General Study Area 9 Localized Study Areas in California 11 Crescent City 11 Butte Sink 15 Grizzly Island 17 Faith Ranch and Los Banos 19 Weather 21 METHODS 23 RESULTS 27 Distribution 27 Fall Migration 27 Aleutian Islands-Alaska Peninsula 27 Northwest Coast 29 Northern California 29 viii TABLE OF CONTENTS (continued) Page Wintering Grounds 33 Sacramento Valley 33 Sacramento-San Joaquin River Delta and Grizzly Island . 37 San Joaquin Valley 39 Other use areas 43 Spring Migration 46 Departure from the Central Valley 46 Occurrence in Humboldt County 47 Crescent City stating grounds 47 North of California 54 Ecology on Main Use Areas 56 Butte Sink 56 Localized use patterns 56 Food items 58 Relation to other wildlife 58 Relation to human activity 59 Grizzly Island 61 Localized use patterns 61 Food items 61 Relation to other wildlife 63 Relation to human activity 63 Faith Ranch 64 Localized use patterns 64 Food items 64 Relation to other wildlife 67 Relation to human activity 67 ix TABLE OF CONTENTS (continued) Page Los Banos 68 Localized use patterns 68 Food items 68 Relation to other wildlife 72 Relation to human activity 72 Crescent City 73 Localized use patterns 73 Food items 77 Relation to other wildlife 77 Relation to human activity 78 Population 79 Documented Mortality 79 Hunting loss 82 Disease 82 Trapping mortality 85 Unknown causes 85 Known Survival 86 Population Levels 88 Fall 1975 88 Spring 1976 89 Fall 1976 91 Spring 1977 91 DISCUSSION 94 Distribution 94 Fall Migration 94 Wintering Areas 97 TABLE OF CONTENTS (continued) Page Spring Migration 102 Ecology on Main Use Areas 106 Localized Use Patterns 106 Food Items 107 Relation to Other Wildlife 107 Relation to Human Activity 108 Population 109 Mortality Factors 109 Mortality Rates and Survival 111 Population Levels 117 Pre-Hunting Closure Population Level 118 Population Increases 118 CONCLUSION AND RECOMMENDATIONS 120 REFERENCES CITED 124 APPENDICES A. Common and Scientific Names of Avian Species from American Ornithologists' Union (1957) and Bellrose (1978) 131 B. Common and Scientific Names of Plant Species from Munz (1959), Mason (1957), and Usher (1974) 132 LIST OF TABLES Table Page 1 Vegetation Types and Dominant Plants at Point Saint George, Reservation Ranch, and McNamara Field 14 2 Monthly Precipitation at Sacramento Weather Station, Winters 1975-76 and 1976-77 22 3 Observations of Migrating Aleutian Canada Geese in the Aleutian Islands, Falls 1976 through 1978 28 4 Unsuccessful Surveys for Aleutian Canada Geese, Falls 1975 and 1976 30 5 Numbers and Time of Occurrence of Aleutian Canada Geese Present at Crescent City, Falls 1975 and 1976 32 6 Occurrence and Flock Size of Aleutian Canada Geese in the Butte Sink, Fall 1976 34 7 Records of Aleutian Canada Geese in the Sacramento Valley, Winters 1975-76 and 1976-77 36 8 Aleutian Canada Geese Observed at Grizzly Island Wildlife Area, Winters 1975-76 and 1976-77 38 9 Daily Counts of Aleutian Canada Geese on the Faith Ranch, 25 December 1976 to 7 March 1977 40 10 Daily Counts of Aleutian Canada Geese on the Nemethi Ranch and Adjacent Areas, 17 January to 13 March 1977 42 11 Records of Aleutian Canada Geese in the San Joaquin Valley, Winters 1975-76 and 1976-77 44 12 Records of Verified and Probable Aleutian Canada Geese along Coastal Humboldt County, February and March 1977 and 1978 48 13 Daily Counts of Aleutian Canada Geese Observed at Crescent City, Spring 1976 49 xii LIST OF TABLES (continued) Table Page 14 Daily Counts of Aleutian Canada Geese Observed at Crescent City, Spring 1977 50 15 Number of Marked Individuals Identified during Observations of Aleutian Canada Geese at Crescent City, Springs 1976 and 1977 53 16 Observations of Migrating Aleutian Canada Geese in the Aleutian Islands, Springs 1975 through 1978 .