A field-friendly alternative to freeze-drying faeces for glucocorticoid metabolite analyses of African wild dogs (Lycaon pictus)

Abstract

Endocrine studies using faeces as hormone matrix have become increasingly popular to examine adrenocortical activity in wildlife. A prerequisite for this approach is to minimize alteration of faecal glucocorticoid metabolite (fGCM) composition post-defecation. This is done by freezing the collected material as soon as possible after collection, and removing moisture from the frozen faecal samples afterwards (usually by freeze-drying). In remote areas, freeze-drying opportunities are often limited, and in the case of the African wild dog ( Lycaon pictus ), established assays revealed that fGCM concentrations remain comparable for only ∼24h post-defaecation. In the present study, three cost-effective drying treatments (exposure to sunlight, placement in a solar oven, and use of a food dehydrator) were investigated as alternatives to the golden standard of freeze-drying faeces. •In comparison to freeze-dried material, African wild dog faecal samples dried through sunlight exposure, a solar oven, and use of a food dehydrator revealed no significant differences in respective fGCM concentrations measured. •A food dehydrator would be the preferable option to dry African wild dog faeces if limited electrical supply is available. This technique dries faeces the fastest, and negates any reliance on weather conditions.