Brigham Young University BYU ScholarsArchive Theses and Dissertations 1951-06-01 Ecology of Passerine birds wintering at Utah Lake Joseph R. Murphy Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd BYU ScholarsArchive Citation Murphy, Joseph R., "Ecology of Passerine birds wintering at Utah Lake" (1951). Theses and Dissertations. 7834. https://scholarsarchive.byu.edu/etd/7834 This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. j!) /,_ ., ) Cvl <::::-.. , rOL ,/I . ,-,:/ _··. , Mi7 \q_5\ ECOLOGYOF PASSERINEBIRDS WINTERINGAT UTAHLAKE A Thesis submitted to the Department of Zoology and Entomology ot Brigham Young University In partial fulfillment or the requirements for the degree of Master of Arts by Joseph R. Murphy June 19,1 ..-: '" Thia thesis by Joseph a. KurphJ 11 accepted 1n its present form by the Special Thesis Committee as satlsty1n1 the thesis requirements tor the degree ot Master of Arts. signed 11 II ACKNOWLEDGEMENTS The completion of this thesis is due in a large part to the aid and assistance which have been rendered to the writer by several individuals and organizations. Appreciation is especially extended to Dr. c. Lynn Hayward, the writer's Special Thesis Committee chairman, and to Dr. B. F. Harrison, committee member. Dr. Hayward has given freely of his time and knowledge in guiding the thesis work; Dr. Harrison has made many valuable suggestions and helped greatly in the identification of plants occurring in the study area. I wish also to thank Dr. Vasco M. Tanner, chairman of the Department of Zoology, and the other members of the depart- ment faculty for the advice and assistance which they have given to the writer for the past several years. I am also grateful to the Salt Lake City office of the United States Weather Bureau who kindly furnished the official weather records which were incorporated in the study, and to the Western Photography Laboratory of the Department of Agri- culture who made available the aerial photograph of the study area. Finally, I wish to thank my wife, who has been most patient in helping with the typing of the manuscript. 111 TABLEOF CONTENTS Page LIST OF TABLES • • • • • • • • • • • • • • • • • • • V LIST OF ILLUSTRATIONS. • • • • • • • • • • • • • • • vi INTRODUCTION• • • • • • • • • • • • • • • • • • • • 1 Previous Literature Area of Study PROCEDUREAND METHODS• • • • • • • • • • • • • • • • 6 FACTORSOF THE PHYSICALENVIRONMENT. • • • • • • • • 11 Temperature Precipitation Wind Sunlight Over-all Seasonal Changes General Summary of Climatic Factors VEGETATIONTYPES • • • • • • • • • • • • • • • • • • 20 Cattail-Bulrush Type Willow Type Wet Meadow Type Dry Meadow Type Deciduous Tree Type COMPOSITIONOF THE AVIFAUNA• • • • • • • • • • • • • 27 Bird Species Present Census Results and Populations Distribution or Birds in Vegetation Types DISCUSSIONOF INDIVI'DUALSPECIES. • • • • • • • • • • 46 SUMMARYAND CONCLUSIONS • • • • • • • • • • • • • • • ,9 LITERATURECITED . 63 iv LIST OF TABLES Table Page I Comparative Weather Data; Long-time Averages Compared to Winter of 19,0-51 •••••••• 12 II Passerine Birds Observed at Utah Lake, Winter ot 1950-,1. • • • • •• • • • • • • • 28-29 III Census Results and Number per Hour f'or Most CommonBirds •••••••••••••••• 31 V LIST OF ILLUSTRATIONS Figure Page 1. Aerial Photograph of the Area or Study ••••• 4 Outline Map or the Study Area, Showing Census Route •••••••••••••••••• 8 3. Growth or Testes as Correlated with Increasing Periods of Daylight ••• • • • • • • 18 4. Plant Types Occurring in the Study Area •• • •• 21 ;. Total Number Recorded for CommonPasserine Birds •• • •••••••••••••••• • • • 33 6. Field Census No. 14. • • • • • • • • • • • • • • 35 7. Field Census No. 24 •• • • • • • • • • • • • • 36 a. Field Census No, 19 ••••••••••••••• 37 9. Field Census No. 48 ••• • • • • • • • • • • • • 38 10. Presence of Passer1ne Birds by Months in the Area or Study ••••••••••• • • • • 40 11. Graph Showing Relative Stability and Instability of Song Sparrow and Redwing ••••••••••• 42 12. Distribution of Passer1ne Birds 1n Vegetation Types •••••••••••••••• 44 13. Field Census No. 47 •• • • • • • • • • • • • • • 48 14. Field Census No. 6. • • • • • • • • • • • • • • 50 Plate I Photographs of Plant Types in the Study Area. • • • • • • • • • • • • , • • • , , 61 Plate II Photographs ot Plant Types in the Stttetf Area• • • • • • • • • • • • • • • • • • 62 vi INTRODUCTION Ornithologists are generally prone to show great inter- est in that period of the life or the bird which embraces the breeding cycle. This interest is perhaps natural, since cli- matic and biologic conditions are nearly ideal for field work and observation during the spring season when most breeding activities take place. Of equal importance, however, and in- deed exerting an even greater biological influence in many respects, is the period covered by the winter months. From an ecological point of view this is one of the most critical peri- ods that the bird must undergo. As a result many birds which are summer residents in areas subject to harsh winters perform the routine and familiar migrations in order that the winter months may be spent under more favorable climatic conditions. There are many kinds of birds which, nevertheless, are known to remain in or near the same general region throughout the various seasons and aspects; these are classified as perma- nent residents. Such groups of birds are often Joined in the late autumn by birds of another category, the winter visitants, who may move in from areas of higher altitude or latitude. In this manner a wintering avian population is established which, in certain areas, may be of considerable size. Such a winter population must be equipped to meet a variety of situations, of both a physical and biological nature. l 2 In the course of the present study the investigator has kept under surveillance the passerine birds which spend the winter months in a certain area adjacent to Utah Lake, near Provo, Utah. The approach to the problem has been largely of an ecological nature, with major stress placed upon such factors as relative numbers or bird species present, distribution or species according to vegetation types, response of birds to climatic changes, movements of birds in the area, and various other phases of their winter habits. The purpose of the thesis which follows is to analyze the data which relate to the above- named factors and draw whatever conclusions appear to be valid. Previous Literature Little previous work has been done on the birds winter- ing in Utah Valley, although Hayward (1935) has contrasted the winter bird lite of Bear Lake (Idaho) and Utah Lake valleys, and further discusses (1948) the birds of the winter aspect in his study of the Wasatch chaparral. These two papers apparently constitute the only published work relating directly to the winter activity of passerine birds in this area. In addition there have been a few seasonal food studies made, particularly those or Liddle (1936) on the rood habits of the English spar- row in Utah Valley, and of Frost (1947) on the food habits of the birds of the Wasatch chaparral. It should be repeated that not a great deal of the above work is applicable to the present area or study. Meager as such local information may be, there has been no dearth of background literature relating to the ecological, 3 physiological, and distributional aspects or birds wintering in other parts of the country, or to winter bird life as a whole. Some of the conclusions drawn from studies which were made in other localities have been utilized in certain aspects of the present work. References will be made to this type of litera- ture throughout the body of the text, wherever such information was drawn upon. Area of Study The area chosen for the study was a relatively narrow segment of the Utah Lake shore lying four miles directly west of the city or Provo. The elevation at this location is 4,490 feet above sea level. Rather definite boundaries were set up to delimit the study area (Fig. l). The north boundary was marked by Provo River, while the southern limit was arbitrarily chosen as a point 1.7 miles south of the river. The open ex- panse of Utah Lake was utilized as the western boundary, while on the east the area was bordered by the Provo airport and culti- vated fields. By way of over-all measurements the area was thus approximately 1.7 miles from north to south, and ranged in east- west width from a minimum of about 100 feet to a maximum of over 1,000 feet when the lake was at its lowest level in the autumn. This particul&r area was chosen for the study for two major reasons. First, it appeared to be an area which would lend itself well to a winter bird population study, since it was almost a separate entity, that is, a relatively undisturbed area surrounded for the most part by cultivated fields; and secondly, the area was readily accessible by automobile, even Fi~. 1.--Aerial photograph of the area of study. The dashed line indicates the boundaries of the study area proper. On the left is Utah Lake, and at the right is the Provo Municipal Airport. Scale: one inch equals 1,000 feet .. 4 5 during the heaviest snows of winter. Lying as it does in such close proximity to Utah Lake, the study area 1s subject to frequent inundations by the waters of the lake with subsequent emergences. In the past there have been great variations in the water level of the lake. For in- stance, during the prol~nged drought period which oceured in the fourth decade of the present century the water level or the lake was so low that it was possible to walk out on the mudflats for at least one-quarter of a mile before encountering water. For the past several years, however, the level of the lake has remained more or less constant, although exhibiting typical seasonal variations.