Kenyon, Julia (1995)
Relationships Between Activity and Sex, Age, Size, and Coloration in the Lizard Sceloporus occidentalis.
Bachelor of Science, Harvey Mudd College, Biology.
Advisor: Stephen Adolph.
Since lizards are ectotherms, their activity is constrained by their thermal environment. Although the environment may allow for many hours of activity per day, lizards are rarely seen for the total time allowed by thermal constraints. Thus, activity is more than a simple manifestation of the lizard’s thermal environment; activity has inherent costs such as mortality and benefits such as increased size. The costs and benefits involved in activity may vary between individuals. I investigated the correlations between activity and age, sex, size, and coloration in the lizard Sceloporus occidentalis. I compared the differences between groups of individuals with the variation between individuals. I found that adults are more active than juveniles, and that males are more active than females. I also found positive correlations between coloration and activity, and size and activity. Juvenile lizards are more often seen on lower perches, such as rocks, than are adults. Additionally, I found that lizards of all age are more active in the middle of the day in the early spring, and that there is a high degree of variation among individual activity patterns.