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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