Abstract:
BACKGROUND : Faecal hormone metabolite measurement is a widely used tool for monitoring
reproductive function and response to stressors in wildlife. Despite many advantages of this
technique, the delay between defaecation, sample collection and processing may influence
steroid concentrations, as faecal bacterial enzymes can alter steroid composition post-defaecation.
OBJECTIVES : This study investigated changes in faecal glucocorticoid (fGCM), androgen (fAM)
and progestagen (fPM) metabolite concentrations in faeces of a male and female African
elephant (Loxodonta africana) post-defaecation and the influence of different faeces-drying
regimes.
METHOD : Subsamples of fresh faeces were frozen after being dried in direct sun or shade for 6,
20, 24, 48 and 72 h and 7 and 34 days. A subset of samples for each sex was immediately frozen
as controls. Faecal hormone metabolite concentrations were determined using enzyme
immunoassays established for fGCM, fAM and fPM monitoring in male and female African
elephants.
RESULTS : Hormone metabolite concentrations of all three steroid classes were stable at first, but
changed distinctively after 20 h post-defaecation, with fGCM concentrations decreasing over
time and fPM and fAM concentrations steadily increasing. In freeze-dried faeces fGCM
concentrations were significantly higher than respective concentrations in sun-dried material,
which were in turn significantly higher than fGCM concentrations in shade-dried material. In
contrast, fAM concentrations were significantly higher in sun- and shade-dried faeces compared
to freeze-dried faeces. Higher fPM concentrations were also found in air-dried samples
compared to lyophilised faeces, but the effect was only significant for sun-dried material.
CONCLUSION : The revealed time restriction for collecting faecal material for hormone
monitoring from elephants in the wild should be taken into account to assure reliable and comparable results. However, if logistics allow a timely collection, non-invasive hormone
measurement remains a powerful and reliable approach to provide information about an
elephant’s endocrine status.
