A field-friendly alternative to freeze-drying faeces for glucocorticoid metabolite quantification in animals of different feeding classes

Abstract

Monitoring stress-related faecal glucocorticoid metabolite (fGCM) concentrations is a reliable, popular and established approach for understanding wildlife responses to perceived stressors. To maintain fGCM integrity post-defaecation, faecal material must be promptly stored frozen, or dried to prevent continued suspected bacterial enzyme activity. We compare the effectiveness of freeze-drying with other field-friendly drying techniques (food dehydrator and homemade solar oven). We collected 10 fresh faecal samples each from nine species (giraffe, impala, blue wildebeest, plains zebra, African elephant, white rhino, cheetah, spotted hyena, and leopard) and monitored alterations in fGCM concentrations over time utilizing these different drying techniques. Our findings indicate that a homemade solar oven is as effective as freeze-drying faecal samples. A food dehydrator is also a suitable method for drying faecal samples for the carnivores monitored. Our findings provide field-friendly methods for researchers dealing with logistical constraints in remote field sites. • For all species examined, a homemade solar oven offers a practical and affordable alternative to freeze-drying faeces for fGCM quantification. • A food dehydrator provides an affordable alternative to freeze-drying faeces for fGCM analysis when monitoring carnivores. • Different faecal sample drying techniques should not be utilized within a single study to ensure comparable analyses of fGCM values.