Date of Award


Degree Type


Degree Name

Departmental Honors




Stress in regards to an animal's social housing environment is well studied in mammals; however there are few studies examining this in reptiles and the results are thus far unclear. For example, behavioral evidence shows adverse effects from individual housing in juvenile chameleons, however physiological measures in whiptail lizards show adverse effects from group housing. Because some reptiles appear to be affected negatively by their social housing environment while others are impacted positively, if we can discover the reason for these differences, we will be able to implement the most effective housing regimes for reptiles. In this study, we tested if male and female side-blotched lizards (Uta stansburiana) experienced physiological changes such as 1) an increase in circulating corticosterone concentrations, an energy-mobilizing hormone indicative of stress, 2) changes in reproductive function and 3) decreasing immunocompetence when housed with and without a conspecific. We found that while there were no significant physiological changes in females, males housed alone had significantly higher corticosterone concentrations than males housed with females, and males housed with a female also had higher testosterone levels. Additionally, group-housed males had relatively reduced immune function when compared to individually-housed males. The difference among sexes might have been a result of stronger territoriality exhibited by males. Furthermore, the difference among species, when comparing this study to previous studies, may be because U. stansburiana are relatively more social reptiles, spending more time with conspecifics in nature, which indicates that the social structure of the species should be accounted for when making housing decisions. Our results suggest that housing male reptiles individually might be stressful, and that males group-housed with female conspecifics maintain higher levels of testosterone indicative of better reproductive function. This group housing is not without cost, however, as animals with elevated testosterone also show reduced immune ability. Therefore, reptile husbandry facilities may wish to take the species in question into consideration as well as the reproductive-immune trade-off when determining housing regimes for reptiles in breeding programs compared to those on exhibit.

Included in

Biology Commons



Faculty Mentor

Susannah French

Departmental Honors Advisor

Kim Sullivan