Determination of steroid hormones in wild bighorn sheep feces cimarrón (Ovis canadensis Shaw) in Baja California Mexico

Abstract

Objective: Determination of steroids hormones in wild bighorn sheep feces with a non-invasive method.

Design/methodology/approach: In this study we analyze progestogens, androgens and estradiol, concentrations in wild bighorn sheep feces of Sierra San Felipe in Baja California during Spring, Winter and Summer seasons of the year 2007. Steroids were quantified by enzime immunoassay and evaluated using a micro titer plate.

Results: With the hormonal profile it was identified that 96 feces were from males and 65 from females. The concentration of progestogens in the feces identified as females varied among the seasons of the year with spring being the highest concentration (280 ng/gr). Progestogen and estrogen concentrations in females increased as environmental conditions improved from winter to spring, coinciding with male androgen increase of 23.78 ng/gr.

Limitations on study/implications: With this method it was not possible to assign the sex of samples that were identified as coming from juvenile individuals. We recommended to analyze fresh feces samples to relate the hormone concentrations with seasonal reproductive events.

Findings/conclusions: The increase in progestogen and estrogen concentrations in feces of females and androgens in males during the spring suggests the initiation of reproductive activity. The concentrations of these hormones in both sexes during the summer are very low (<5 ng/gr), which suggests low reproductive activity