Insights from steroids measured in wildlife hair, feathers, and claws

Life history traits contribute to individual fitness. They show diverse trade-offs between growth, survival, and reproduction. Steroids may be involved in the mechanisms mediating these trade-offs via participation in reproduction, growth, and development, or as coordinators, adjusting behaviours to circumstances and contexts. Steroid concentrations can provide information to conspecifics (and researchers) on individual’s physiological and social condition. While rapidly changing steroid levels reflect internal states, their lability presents a challenge to quantification. In the last two decades, this challenge led to the validation of non-invasive matrices that reflect longer time frames that are not influenced by the stress involved in capture and handling.

Keratin-based matrices, such as hair, feathers, claws, and nails, are increasingly being used as a tool for quantifying endogenous steroids in wildlife and domestic animals. The main advantage of this approach is that it provides a long-term record of steroid hormone concentrations integrated over the period of growth. Since samples are unaffected by the momentary stress of collection, they are appropriate for studying long-term effects of stable social, physiological, nutritional, and environmental conditions, baseline levels, and chronic stress. In this talk, I will focus on the opportunities that hair-, claw-, and feather- testing have opened in studying natural (e.g., predators, parasites, weather, food availability, disease, social conflict) and anthropogenic stressors (e.g., populations that are hunted, suffer habitat fragmentation, or are disturbed by environmental contaminations).