Biology ETDs

Publication Date

Summer 8-1-2023



The study of thermoregulation is of growing concern in this era of rapid climate change. Earlier studies such as those pioneered by Scholander and Bartholomew directed focus toward the study of endotherm survival in conditions of cold weather adversity. As techniques evolved in the measurement of parameters quantifying thermoregulation, metabolism and energy allocation, the standardization procedures has increased the comparability of data from diverse taxa.

We can now search historical records and current research for explanations to the changes in the distribution, migration, extirpation or survival of animal and plant populations through time. It is increasingly common to observe dramatic changes to ecosystems within a human lifetime.

The warming of the planet is a major contributor to the challenges an organism now faces. At the edge of tolerance are the conditions where the environmental temperatures exceed the body temperature of the organism. Endotherms must control body temperature not only for survival but to allow resources for growth and reproduction if populations are to be maintained. Aridity is another major challenge, since the only way to control body temperature in environmental heat that exceeds it, is by the evaporation of water.

Much data has been accumulating recently among collaborators working in the word's hottest deserts while exploring the physiology and behavior that permits survival in these climate extremes. Nocturnality does not infer protection from environmental heat for several reasons. Nocturnal minimal temperatures globally are increasing more rapidly than diurnal maxima. Roosting and nesting habits expose many nocturnally active endotherms to varying degrees of diurnal heat gain. Adverse outcomes of heat waves are more closely related to high nocturnal minima than to high diurnal maxima.

Using standardized techniques of flow-through respirometry, I have examined heat tolerance, metabolism and water loss in three groups of nocturnally active, flying endotherms that inhabit hot deserts and observed some behavioral and physiological correlates to their adaptation to the trade-offs between dehydration and hyperthermia imposed by the extremes of heat and aridity. Nightjars, owls and bats are the

subjects of this endeavor.




Strigiformes, Caprimulgiformes, Chiroptera, Respirometry, Evaporative water loss, Resting metabolic rate, Body temperature, Heat tolerance limit

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

Blair O. Wolf

Second Committee Member

Christopher C. Witt

Third Committee Member

Ernest W. Valdez

Fourth Committee Member

Liam P. McGuire

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Biology Commons