Differences in Basal Metabolic Rates, Heart Masses, and Hematocrits of Bats, Terrestrial Mammals, and Birds

Graduation Year


Date of Submission


Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts


W.M. Keck Science Department

Second Department


Reader 1

Marion Preest

Reader 2

Lars Schmitz

Rights Information

© 2014 Brett Kaoru Watanabe


Bats are the only mammals capable of powered flight. In flight, bats consume up to 20 times more oxygen per hour than under basal conditions. This is twice the increase reported for running mammals of the same body sizes. Birds are the only other group of vertebrate capable of powered flight. By plotting morphological and physiological parameters against body mass for bats, terrestrial mammals, and birds, we can observe to what extent these parameters permit high rates of oxygen delivery necessary for flight.

In this study we analyzed basal metabolic rate, heart mass, and hematocrit, and compared how differently they scale in the afore-mentioned groups. We found that larger heart masses are associated with the ability to fly; hematocrit values for birds change markedly with body size, while those for mammals and bats are nearly independent of body size; and that BMR scales differently in all three groups.


This thesis has been removed to protect sensitive data per request of the Keck Science Dept. Interim Dean. 2017-05-03

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This thesis is restricted to the Claremont Colleges current faculty, students, and staff.