Contents

Page
[Introduction]1
[Defining the Problem]1
[Procyonid Origins]1
[Typical Procyonids]2
[The Atypical Procyonid]3
[The Hypothesis]4
[Hypothesis Testing]4
[Adaptive Significance of the Variables]4
[Basal Metabolic Rate and Intrinsic Rate of Natural Increase]4
[Minimum Thermal Conductance]4
[Capacity for Evaporative Cooling]5
[Diet]5
[Experimental Design and Summary]5
[Acknowledgments]5
[Materials and Methods]6
[Live-trapping]6
[Metabolic Studies]6
[Basal and Thermoregulatory Metabolism]6
[Evaporative Water Loss]7
[Body Temperature]7
[Calibrations]7
[Calorimeter]7
[Body Temperature Transmitters]8
[Statistical Methods]8
[Estimating Intrinsic Rate of Natural Increase]8
[Comparison of Adaptive Units]8
[Results]8
[Body Mass]8
[Basal Metabolic Rate]9
[Minimum Thermal Conductance]9
[Evaporative Water Loss]11
[Thermoregulation at Low Temperatures]12
[Body Temperature]12
[Summer]14
[Winter]14
[Thermoregulation at High Temperatures]16
[Body Temperature]16
[Summer]16
[Winter]16
[Daily Cycle of Body Temperature]16
[Discussion]16
[Basal Metabolic Rate]16
[Background]16
[Captive versus Wild Raccoons]17
[Seasonal Metabolism of Raccoons]17
[Comparison of Procyon lotor with Other Procyonids]17
[Influence of Diet on Basal Metabolism]18
[Background]18
[Food Habits of Procyonids]18
[Food Habits and Basal Metabolism]19
[Summary]19
[Basal Metabolism and Intrinsic Rate of Natural Increase]19
[Background]19
[Procyon lotor]19
[Bassariscus astutus]19
[Nasua narica]19
[Nasua nasua]20
[Procyon cancrivorus]20
[Potos flavus]20
[Summary]20
[Basal Metabolism and Climatic Distribution]21
[Procyon lotor]21
[Other Procyonids]21
[Minimum Thermal Conductance]21
[Background]21
[Effect of Molt on Thermal Conductance]21
[Comparison of Thermal Conductances]22
[Procyon lotor versus Tropical Procyonids]22
[Bassariscus astutus]22
[Thermoregulation and Use of Stored Fat at Low Temperatures]22
[Background]22
[Thermoregulation]22
[Stored Fat]23
[Thermal Model of the Raccoon and Its Den]23
[Metabolic Advantage of the Den]23
[Thermoregulation at High Temperatures]24
[Background]24
[Comparison of Procyonid Responses to Heat Stress]24
[Potos flavus]24
[Nasua nasua and Nasua narica]24
[Bassariscus astutus]24
[Procyon lotor]24
[Procyon cancrivorus]24
[Summary]24
[Composite Scores of Adaptive Units and Geographic Distribution]25
[Evolution of Metabolic Adaptations]26
[Evolution of Low Basal Metabolic Rate]26
[Evolution of High Basal Metabolic Rate]27
[Summary]28
[Appendix: List of Symbols]29
[Literature Cited]30

Metabolic Adaptation to Climate
and Distribution of the Raccoon
Procyon lotor and Other Procyonidae

John N. Mugaas, John Seidensticker,
and Kathleen P. Mahlke-Johnson

John N. Mugaas, Department of Physiology, Division of Functional Biology, West Virginia School of Osteopathic Medicine, Lewisburg, West Virginia 24901. John Seidensticker and Kathleen P. Mahlke-Johnson, National Zoological Park, Smithsonian Institution, Washington, D.C. 20008.