THE LIFE HISTORY AND ECOLOGY OF THE BOG LEMMING, SYNAPT0MY5 COOPERI, IN SOUTHERN NEW JERSEY By Paul F. Connor A THESIS Submitted to the College of Advanced Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfiUment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Zoology 1957 ProQuest Number: 10008535 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. uest ProQuest 10008535 Published by ProQuest LLC (2016). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 f t a ACKNOWLEDGMENTS I wish to thank Dr. Don W. Hayne for his critical read­ ing of the manuscript and many helpful suggestions. Gratitude is expressed to Dr. Rollin H. Baker, Dr. William B. Drew, and Dr. T. Wayne Porter, for their assistance. Grateful acknowledg­ ment, is made to Dr. Richard H, Manville, for encouragement during initial phases of the. research, and to Dr. Karl A. Stiles, Head of the Department of Zoology. Thanks are expressed to Dr. John E. Cantlon, and to Dr. Jack McCormack of the American Museum of Natural History, for identifying certain plant material. Appreciation is due Michigan State University for the fellowship granted in support of the study. Finally, many thanks are due my wife, Martha T. Connor, for her help. THE LIFE HISTORY AND ECOLOGY OF THE BOG LEMMING, SYNAPTOMYS COOPER I, IN SOUTHERN NEW JERSEY By Paul F. Connor AN ABSTRACT Submitted to the College of Advanced Graduate Studies of Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Zoology Year 1957 Approved ABSTRACT A study of the bog lemming, Synaptomys cooperi, was undertaken during parts of 1953> 195U* and 1955 in the bogs of the New Jersey pine barren region. Methods of study included snap-trapping, live- trapping, field observations, and observations of animals in confine­ ment. Average and range of weights and external measurements are given for 52 adult males and 31 adult females. Counts of plantar pads and mammae were made and general characteristics of hip glands and pelages were noted. One hundred and forty bog lemmings were trapped in 20 spaghnum bogs, in pine woods adjacent to several of the bogs, and in one dry field. In the bogs, wherever there was a stand of sedge and shrubs Synaptomys was likely to be present^ in several such areas Synaptomys was the most numerous microtine trapped. The habitats of the study areas are described, including the physical environment, plant species small mammal associates, and other animals present. In several areas during the colder months most lemming activity shifted from the bogs to adjoining pine woods. Thirty-eight of the bog lemmings were taken in live traps, with a total of 190 captures and recaptures of these individuals. Two areas which were live-trapped gave information relating to home range. Centers of activity were computed and apparent home ranges were mapped Approximate trap-revealed ’’minimum home range” and maximum distance between captures are given for 10 individuals. Some home ranges included both wet and dry habitat at the same time. Territoriality and population density is discussed. In trapping, considerably more males than females were taken. Three of the animals marked in the fall were re-taken the next spring* Abundance of sign was estimated and recorded for 20 areas at different seasons. Two principle methods used in studying food habits were analyses of the contents of digestive tracts and observations of cuttings and other signs. Eighty-six stomachs were examined. A list of 27 plant species and parts consumed is presented. Stomach contents are given in frequency occurrence, per cent frequency occurrence, and per cent of total bulk. Field observations of cuttings and chewings of various plants are discussed in detail. Observations were made of certain habits associated with feeding. Fifteen nests are described, including nests containing young at time of discovery. Surface runways, subsurface tunnels, and chambers were studied and measured. Detailed description of sign is given. The sign was believed to be distinctive and usually separable from that of Microtus pennsylvanicus in southern New Jersey. Observations of caged animals were useful in obtaining information relating to reproduction, development, and behavior. Individuals lived up to a year in captivity. Synaptomys was bred for the first time in captivity so far as I know. Six litters (22 young) were born in'captivity to one female v during a five-month period. The gestation period was 23 days in one case and was believed to be 23 days in another. Information relating to number of young per litter was obtained from embryo counts, placental scar counts, and litters born in the wild and in captivity. Three nests containing a total of 10 young were found in the wild. Breeding season based on trapped animals is discussed. Parental care, including building and repair of nests, is described. The growth and development of 28 young were studied in the laboratory. Condition at birth, and weights, measurements, pelages, molts, external features, and behavior at various stages of growth are given. Observations are reported on the behavior of bog lemmings in the field and laboratory, including times of activity, movements, voice, sanitation, and temperament. vi TABLE OF CONTENTS Page INTRODUCTION........................... 1 AREA AND GENERAL METHODS.................................. 3 DESCRIPTION OF ADULTS..................................... 5 General Description........................... 5 Weights and Measurements ........ 6 Plantar Pads....................................... 8 Mammae ................ 8 Hip Glands...................... 9 Pelage...... 10 ECOLOGY................................................ 13 Geographical Distribution.............................. 13 General Habitat Preference ....................... 15 Seasonal Variation in Habitat........................... 17 Description of Habitat...... 20 Physical Environment ............................. 20 Plant Environment ........... 26 Effects of Animals1 Activity on Plant Environment....... 35 Animal Environment ......... 35 Relationships with Man.............................. 57 POPULATIONS............................................. 59 Sex Ratios and Age Classes..,........ 59 Sex Ratios ...... 59 Age Classes........................................ 5l Longevity and Mortality....... 51 Longevity...... 5l Causes of Mortality................................. 52 Home Range........ 53 Materials and Methods used in Studying Home Range ... 53 Discussion of Home Range....... 57 T erri toriali ty ............................. 65 Population Density.................................... 66 Estimated Density Figures...... ............... 66 Variations In Density. .................. 6b vii TABLE OF CONTENTS - Continued Page REPRODUCTION................................... ......... 76 Courting^ Mating, and Associated Habits................. 76 Period of Gestation......................... 77 Number of Young.... ................... 78 Dates of Breeding...................................... 80 Family Life...... 83 GROWTH AND DEVELOPMENT OF YOUNG............................ 88 Condition of Young at Birth...... 89 Weights and Measurements............................ 91 External Features.................................... 97 Pelage............................................... 99 Comparison.With Microtus Young............................ 103 Behavior ........................................... 10 5 FOOD HABITS............................................... 107 Review of Literature of Food Habits....... 107 Methods Used in Studying Food Habits..................... 109 Discussion of Foods Eaten......... 109 List of Food Species and Parts Consumed.................. 109 Food Preferences and Foods at Different Seasons.. 110 Substitute Foods Eaten in Captivity...... 129 Habits Associated with Feeding........... 130 NESTS, RUNWAYS, AND SIGN................................... 137 Nests..... ................... 137 Runways, Tunnels, and Chambers........................... 155 Sign............................ ...................... 157 BEHAVIOR................................................ 153 Times of Activity......................... 153 Movements and Locomotion.............................. 155 Voice and Other Means of Communication......... 156 Cleanliness (Sanitation)........... 160 Sociability......... 161 General Temperament Observed in Confinement.................l6l SUMMARY....................... 165 LITERATURE CITED......................................... 172 viii 1 INTRODUCTION Bog lemmings of the genus Synaptomys (Tribe Leminij Subfamily Micro- tinae) are widely distributed over northern North America. Synaptomys borealis, the northern bog lemming, ranges throughout much of Alaska and Canada. Synaptomys cooperi, the southern species, occurs from Canada south to Kansas, Arkansas, and North Carolina. Within this vast area it inhabits a large variety