The Metabolic Cost of Forward Flight in Anna's Hummingbirds
Author: Mauricio Cruz
Faculty Supervisor: Derrick Groom
Department: Biology
Knowing the energetic cost of locomotion is very important for predicting animal behavior but one of the biggest obstacles that bird physiologists face is measuring energy costs during flight that are representative of natural conditions. Traditional methods of measuring flight energy costs require the attachment of equipment to the animal, which could disrupt normal flight behaviors. My research focuses on overcoming this obstacle by using a relatively new, non-invasive technique to measure the cost of flight in Anna's hummingbirds using a bolus dose of isotope-labeled bicarbonate. The labeled bicarbonate equilibrates with the animal’s bicarbonate pool, allowing for the estimation of metabolic rate via measurement of the relative rate of labeled bicarbonate loss. The major advantage of the sodium bicarbonate method is that it does not require the use of equipment attached to the animal. The findings from this project will hopefully contribute to predicting hummingbird behavior over a wide range of ecological contexts, which is increasingly relevant as the range of the Anna's hummingbird continues to expand as a result of anthropogenic environmental changes.