Non-invasive monitoring of reproductive status in wild mongoose lemurs (Eulemur mongoz)

Abstract

Endocrine profiles were investigated in wild and captive mongoose lemurs (Eulemur mongoz; Lemuridae) by analysing faecal progestagens and oestrogens. Oestrous cycle characterization was not possible, as most females appeared to conceive during the first oestrus of the breeding season. Conception was preceded by a pseudo-oestrus with no discernible luteal phase. Pseudo-oestrus and oestrus identification was possible by investigating the oestrogen : progestagen ratio. Pregnancy was reliably determined approximately 47 days after conception, when progestagen and oestrogen excretion increased above breeding season concentrations. Gestation was further characterized by high progestagen concentrations and a decline in oestrogen excretion 70–80 days after conception. Post partum, progestagens declined, but oestrogen excretion increased to exceed breeding season concentrations. In the wild group, a nulliparous daughter conceived while still a member of her natal group and aborted after 70–80 days of pregnancy at which time progestagens had declined but oestrogens remained high. Comparisons with other strepsirhine primates suggest that pseudo-oestrus followed by conception at first oestrus may be prevalent in lemurs. Gestational progesterone profiles vary between species, but a delayed increase in oestrogens during pregnancy could be common to all strepsirhines, although oestrogen levels during the final trimester of pregnancy differ between lemurs and lorises. Methodological investigations showed that prolonged storage of faeces in ethanol is viable and that the presence of undigested vegetable matter in the faecal pellets had no effect on the interpretation of hormone profiles.