2023 135 ENV

The Relative Importance of Thermoregulatory Mechanisms in Hummingbirds during Physical Activity and Temperature Change

By: Alexa Quintero

Department: Biology

Faculty Advisor: Dr. Derrick Groom

Hummingbirds have unique physiological and morphological adaptations, including their ability to fly at high speeds and hover in place. These adaptations are supported by their high metabolisms, which generate body heat that must be dissipated. The relative importance of the different thermoregulatory mechanisms (conduction, convection, radiation, and evaporation) of hummingbirds is poorly understood, especially under different thermal conditions in the environment. We aim to characterize the significance of various thermoregulatory mechanisms in hummingbirds under conditions of both thermal and exercise stress. We will use this data to examine physiological strategies for the maintenance of thermal balance, with the goal of understanding avian adaptation to diverse conditions. We hypothesize that hummingbirds employ a combination of panting, evaporative cooling, and changes in subcutaneous blood flow to regulate body temperature during exercise and in different thermal conditions. Thermal imaging and respirometry will be used to quantify heat transfer across various temperatures and in different modes of flight. Results are expected to indicate that heat is dissipated in the ocular and axial regions, and the feet. Furthermore, evaporation is expected to be the primary heat dissipation method at high ambient temperatures. This study will add to the body of knowledge surrounding the heat dissipation strategies evolved by hummingbirds, which will inform how they might adapt to the increasing temperatures presented by climate change.