Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1956 Hour-To-Hour Variation in the Volume of Nocturnal Migration in Autumn. Robert James Newman Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Newman, Robert James, "Hour-To-Hour Variation in the Volume of Nocturnal Migration in Autumn." (1956). LSU Historical Dissertations and Theses. 178. https://digitalcommons.lsu.edu/gradschool_disstheses/178 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. HOUR-TO-HOUR VARIATION IN THE VOLUME OF NOCTURNAL MIGRATION IN AUTUMN A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Zoology by Robert James Newman B.A., University of Pennsylvania, 1928 M.S., Louisiana State University, 1951 August, 1956 ACKNOWLEDGMENTS The investigations described in the pages that follow have been a cooperative undertaking. So many people have contributed so gener­ ously and in so many ways to the success of the study that it is impossible to pay proper tribute to them all. Nine hundred and nine bird students and astronomers spent an estimated 3>500 man-hours, working far into the night, to secure the field data on which the analyses are based. These observers are listed on pp. 138-151 of this report. On behalf of the Louisiana State University Museum of Zoology, and on ray own behalf, I wish to express to all these people our continuing gratitude for an accomplishment that has no close parallel in the history of bird study. The organizing of the observation network was likewise a joint endeavor. Nearly every ornithological journal in the United States gave space to notices of the project, and the very numbers of the people who worked to enlist the help of others in their communities make8 specific acknowledgment of their contributions impossible. I t would be remiss indeed, however, not to make special mention of the part played by Elizabeth S. Manning, Associate Editor of Audubon Field Notes, who made that publication a medium for periodic announcements concerning the project; by Kenneth D. Morrison, Editor of Audubon Magazine, who carried on a campaign of his own. to interest the various ii iii local branches of the National Audubon Society in the program; and by Mr s. William G. Irving, Chandler S. Robbins, and James A. Zimmerman, each of whom undertook a statewide correspondence with potential participants. Throughout the organizational phase of the work, the Louisiana State University Bureau of Public Relations placed its facilities at the disposal of the project. Statistically trained members of the staff and faculty of the University who have offered profitable suggestions regarding the analysis of data include Dr. P. F. Boyer, Director of the Bureau of Business Research, Dr. Bernard M. Bass and Dr. Frank M. Dumas of the Department of Psychology, and Jerry M. Law and J. P. Montgomery of the Agri­ cultural Experiment Station. Mr. Law has been especially liberal in the time he has devoted to the problem. Valuable technical assistance of other sorts has been given me by Dr. David V. Guthrie and Kenneth M. Yoss of the Department of Physics and Astronomy. Among those who have assisted with the mathematical calculations involved in the study, I want particularly to commend the work of Mr. and Mrs. Louis Freeman, who donated their efforts to the project, of Mrs. Frances James, who was also untiring in her efforts as an observer, and of Mrs. Betty Goldberg, whose efficiency in computation was a major factor in bringing the study to its present stage of completion. Professors Ellinor H. Behre, Harry J. Bennett, H. Bruce Boudreaux, J. Harvey Roberts, and Oscar W. Rosewall, all of the faculty of the Department of Zoology, have kindly taken time to examine the manuscript critically and furthermore have actively participated in the field work. Professor George H. Lowery, Jr., Director of the Louisiana State University Museum of Zoology, has supervised the research from its beginning to its present stage. The opportunity to work with him and to make use of the techniques of migration study that he developed has been a very great privilege. I am further indebted to the Bausch and Lorab Optical Company for the loan of six new Balscopes for distribution at critical points in the observational network and to the Department of Psychology at Louisiana State University for permission to make use of their auto­ matic calculating machines. TABLE OF CONTENTS PAGE TITLE PAGE.................................................. i ACKNOWLEDGMENTS.............................................. ii TABLE OF CONTENTS............................................ ▼ LIST OF TABLES............... ............................... viii LIST OF FIGURES.............................................. ix ABSTRACT......................................... xii INTRODUCTION................................................. 1 THEORETIC ASPECTS OF HOUR-TO-HOUR VARIATION................... 9 Assumed effect of the moon's altitude on bird counts.......... 10 The angle of incidence.............. 12 The effect of containing lines......... 15 The effect of distributional gaps.......... 16 Probability and observed migration peaks*................... 19 The effect of changing ground speed .................. 21 GENERAL PATTERNS OF HOURLY AVERAGE FLIGHT DENSITY............. 23 The correction principle * 23 Averaging out local variations................ ............. 25 The spring pattern of hourly average flight densities........ 26 Autumnal data: selections 1 and 7 .......................... 30 v r vi PAGE The fall pattern of hourly average flight densities.......... 31 The average pattern for spring.................. 36 The average pattern for autumn............................. 37 Hours of peak density............ 41 GEOGRAPHIC VARIATION IN HOUR-TO-HOUR FLIGHT DENSITY PATTERNS.... 44 The method of analysis.................................... 45 North and south compared................................... 46 Baton Rouge and the rest of the south compared........... 49 The Far West and Canada.................................... 52 Memphis and Little Rock. ........ 55 The effects of geographic position........................... ' 55 VARIATION WITH MONTH AND WITH THE NIGHTLY VOLUME OF MIGRATION... 58 Monthly variations in flight density pattern........ 58 Pattern and the volume of the night's flight......... ....•••• 62 Classifying sets according to migration volume.............. 63 Patterns of the percentage groups. ............ 64 Is the pattern modified by the time of twilight? ......... 70 Effects of day-length on pattern............. 71 OTHER FACTORS INFLUENCING HOURp-TO-HOUR PATTERNS............... 74 Variation of pattern with date in lunation.................. 74 Variation in pattern with the maximum altitude of the moon.... 77 Variation in pattern with flight direction.................. 80 ARE FLIGHT DENSITIES TRUE MEASURES OF MIGRATION? ............. 85 The rhythm hypothesis................. 85 vii PAGE The factor curve ............. *............ 87 Patterns of time-adjusted counts............................ 90 Assumptions in the flight density hypothesis ..... 93 An alternative view of the effect of the moon on sampling..... 95 The 15-night tests......................................... 96 The problem of contamination............. .................. 99 Counts of flight calls........... 104 SUMMARY AND CONCLUSIONS .............................. 107 APPENDIX.................................................... Ill Basic data.......... Ill Flight densities and time-adjusted counts................. Ill Additional station data................................. 138 The selections....... 152 Details of procedure.................. 163 Observational forms...................................... 163 The tallying procedure ...... 164 Computation of altitudes and azimuths.»•••••.............. 168 Ascertaining flight.directions.................. 170 Computing flight densities.......................... 177 Flight density summary. ......... 182 Adjustments to average magnitude....... .................. 182 LITERATURE CITED............................................ 185 BIOGRAPHY................................................... 187 LIST OF TABLES TABLE PAGE I. Hourly Flight Densities and Time-Adjusted Counts......... 113 II, Hourly Numbers of Sets in Each Selection................. 159 III. Average Date, F - Value, Magnitude, Latitude, and Peak Altitude for Each Selection. ................ 161 IV. Flight Paths and Their Equivalents through Center.......... 167 viii LIST OF FIGURES FIGURE PAGE 1* Assumed effect of the altitude of the moon on lunar bird counts....................... 11 2. Effect of directional angles on lunar bird counts....... 13 3* Location of observation stations concerned in this study... 27 4* Hourly average flight densities in spring................ 29 5. Hourly average flight densities in autumn: from the area of the spring study.............................. 32 6. Hourly average flight densities as percentages: