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.
Myxomatosis in the Mallee region of Victoria, Australia