The effects of repeated handling and corticosterone treatment on behavior in an amphibian (Ocoee salamander: Desmognathus ocoee)

Abstract

Exposure to unpredictable challenges triggers a stress response that helps an animal cope by ensuring energy availability and increasing expression of anti-predator behaviors. At the same time, stress responses typically suppress activities non-essential to immediate survival, such as growth and reproduction. Glucocorticoid hormones are key mediators of the stress response. We measured the effects of repeated exposure to a handling stressor and repeated elevation of plasma levels of the glucocorticoid hormone, corticosterone (CORT) in a terrestrial salamander, Desmognathus ocoee. Subjects were handled daily or treated every day with a dermal patch containing CORT. Compared to control treatments, chronic handling and treatment with CORT both resulted in decreased body weight. Repeated handling, but not treatment with CORT, reduced feeding in females and activity in both males and females. Treatments had no effect on white blood cell differentials. Despite a nonsignificant trend for courtship to be delayed in handled animals, most salamanders in all treatment groups courted and mated. Courtship and mating may be relatively resistant to the effects of repeated handling and elevated plasma CORT because courtship and mating are energetically inexpensive in this species.