2023 133 ENV

Measuring Evaporative and Respiratory Water Loss in Calypte anna’s Hummingbirds

By: Cecilia Doan, Christian Guerzon

Department: Biology

Faculty Advisor: Dr. Derrick Groom

Climate change is impacting the survival of animals through a number of mechanisms, one notable way is through increases in temperatures and heat wave events. During these heat flashes, endothermic animals like birds and mammals use various strategies to regulate their body temperature, and evaporating water from the body surface is one of the critical mechanisms they employ. There are two primary routes of evaporative water loss: cutaneously through the skin such as sweating in mammals and through evaporating water across the skin in birds, or through the moist air being exhaled during respiration. The objective of this study aims to investigate the importance of the two evaporative water loss routes for regulating the body temperature of Anna's hummingbirds (Calypte anna). The head and the body will be partitioned from one another, and respirometry will be performed on the head and body in isolation to measure rates of evaporation. Each bird will be exposed to different temperatures as a thermal challenge, and while measuring them when in a low versus high hydration state. It is expected that respiratory water loss will be the primary mode of water loss for Anna’s hummingbirds, with cutaneous water loss playing a supporting role. By understanding the physiological regulation of endothermic animals like birds, this study can provide valuable insights into their ability to cope with climate change-induced temperature changes. Overall, this study can contribute to our understanding of the effects of climate change on animal physiology and inform conservation efforts about the survivability of species.