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Fecal Testosterone Metabolites Were Highest in 24–36-Month-Old Male Northern Palm Civets

Northern palm civet walking through green grass
Research · Physiology

Fecal testosterone metabolites were highest overall in 24–36-month-old male northern palm civets (Paradoxurus hermaphroditus) in a 12-month captive study in Vietnam. Fifteen clinically healthy males were divided into three age groups — 12–24, 24–36 and 36–48 months — with five animals in each group and all housed individually under similar conditions.

Testosterone is an androgen involved in male reproductive functions including sexual maturation, sperm production and reproductive behaviour. Instead of repeatedly taking blood, the researchers collected fresh faecal samples every month and measured testosterone metabolites with ELISA, an antibody-based laboratory assay. This allowed endocrine activity to be followed repeatedly without handling the animals for blood sampling.

The 24–36-month group had the highest levels

Across most months, males aged 24–36 months had higher fecal testosterone-metabolite concentrations than the younger and older groups. They also had the highest average concentrations in both seasons. In this study, the age pattern therefore pointed to stronger reproductive endocrine activity in the middle age group.

The result should not be read as establishing a fixed reproductive peak age for the species. Only five animals were included in each age group, and the study did not combine the hormone measurements with semen quality, mating behaviour or reproductive success. The author identifies these as important areas for larger follow-up studies.

Seasonal patterns differed among age groups

Monthly concentrations generally declined from January toward June and then increased later in the year, with the highest values recorded from September to December. For the seasonal comparison, the study defined the dry season in southern Vietnam as December–April and the rainy season as May–November.

The 12–24- and 24–36-month groups had higher average concentrations in the dry season than in the rainy season, while the 36–48-month group showed no clear seasonal difference. The monthly late-year rise and the dry-versus-rainy comparison describe different aspects of the same annual data and therefore do not mean that every month of the dry season had higher values than every rainy-season month.

Faecal metabolites provide a non-invasive endocrine measure

Hormones are metabolised before their breakdown products are excreted in faeces, so these samples provide an indirect measure of reproductive endocrine activity rather than an instantaneous blood-testosterone value. Their main advantage is that the same captive animals can be sampled repeatedly with much less disturbance.

The study therefore provides baseline information on age- and season-related endocrine variation in captive male northern palm civets. Its conclusions apply to the small captive sample studied and provide a basis for testing how hormone patterns relate to reproductive performance in larger groups.

Sources and image credit

  1. Nguyen, T. T. H. (2026). Effects of age and seasonal variation on fecal testosterone concentrations in captive common palm civets (Paradoxurus hermaphroditus). European Journal of Ecology, Biology and Agriculture, 3(3), 279–287. https://doi.org/10.59324/ejeba.2026.3(3).26Primary open-access research article published 21 June 2026. Fifteen captive healthy male Paradoxurus hermaphroditus in three age groups were sampled monthly for 12 months. Seasons were classified according to local climatic conditions in southern Vietnam, and fecal testosterone metabolites were measured by ELISA.

Image: Praveenp / Wikimedia Commons — wild northern/common palm civet (Paradoxurus hermaphroditus) photographed in Kottayam district, Kerala, India, 3 October 2009; uncropped original; representative species image, not one of the captive study animals · CC BY-SA 3.0 · Source

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