ADAPTIVE ASPECTS OF ACTIVITY RHYTHMS IN BATS 1 (,K(>k<;i<: DECOURSEY AND PATRICIA j. DECOURSKY siul,'uictil Institute, I'nifcrsity i>f TiU'iin/cn , (icnnany. and tJic Zoolin/y 1 icpiirfiiit-iit. l'ni:-crsity of ll'isconsin, Madison 6, H'isconsin A daily cycle of activity in animals was first noted centuries ago, but only in the past decade has substantial progress been made in analyzing the complex interaction of physiological and environmental regulatory factors. Research in circadian physiology indicates that an endogenous timing system, coupled with some daily recurring agent of the environment, provides the basis for activity rhythm regulation of many species (Aschoff, 1958, 1960; DeCoursey, 1961; Pittendrigh, l''i>0). For some of the remaining problems, bats afforded several unique and promising approaches. Since bats are strongly nocturnal, but generally depend upon auditory rather than visual stimuli (Griffin, 1958), they were of particular interest for determining the effectiveness of the daily light cycle as an activity synchronizer. Furthermore, their preference for roosting in caves, and dimly lit buildings, pro-vided opportunities for studying environment-testing behavior, and for demonstrat-ing the ecological value of circadian rhythms. Results are presented here for experiments in the laboratory and in natural habitat. The research was carried out under the auspices of the Zoophysiological Enstitute of the University of Tubingen, Germany ; it is a pleasure to acknowledge the gen-erous assistance of the Director, Professor F. P. Moehres. We extend our thanks also to the Institute's staff for help with many phases of the work; to Dr. Rolf Gogel, Pastor in Wendelsheim, Germany, for his hospitality and cooperation which made possible the studies of the Myntis uiyutis colony; to Professor Jiirgen Aschnff of the Max-Planck Institute, Frling, Germany, for making available recording apparatus: to Professor Leo Pardi of the University of Turin, Italy, for help in collecting the Rhinolophus; and to the Zoology Department of the University of Wisconsin, especially to Professor John Emlen, for furnishing working accom-modations during the preparation of the manuscript. Dr. James King and Dr. 1 lorst Schwassmann gave helpful suggestions for the manuscript. Financial support was granted to the senior author through Public Health Fellowship No. BF-1 1,999 from the National Institute of Neurological Diseases and P.lindness. of the United States National Institutes of Health. /'art I : Experimental laboratory studies Material and methods The greater European horseshoe bat, Rhinolophus jerrum-equinum, can be maintained in small rooms over long periods of time in good health, and its daily ddro^ : /oniony I Vpartmrnt, Washington State University, Pullman. Washington. 14
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