Female M. parma in captivity reach sexual maturity at 11 1/2-16 months of age.
Scrota1 size indicates that sexual maturity is attained in males at about 22 months. One
male had spermatozoa at 19-20 months and another had a first fertile mating at 24-25
months.
Mating behaviour is described and resembles that of other small macropodids.
M. parma is monovular and polyoestrous. The oestrous cycle has a mean length
of 4197810.72 days (n = 58; range 36-59 days) while the gestation period is
34.54*0.13 days (n = 28; range 33-36 days). Post-partum oestrus and mating
occurred from 4 to 13 days after birth in a small proportion (16.7%) of those animals
examined. However, most animals had an oestrus, while carrying a pouch young,
between 45 and 105 days after birth. A few animals did not come into oestrus at all
while carrying a pouch young.
Removal of pouch young typically resulted in return to oestrus between 6 and
15 days later, in females that had not had a post-partum oestrus or an oestrus while
carrying a pouch young. Females which mated at some stage during lactation prior to
removal of pouch young gave birth 31.16 days later (n = 3; range 30.5-32.0 days).
Three females at the Melbourne Zoo had estimated delayed gestation periods of 31, 31,
and 32 days.
The earliest observation of a young with its head out of the pouch was at 146 days
of pouch life. Most young had left the pouch for short intervals by 175 days with the
youngest observed out at 160 days. Young permanently leave the pouch at 211.9+-1.0
days (n = 10; range 207-218 days). Permanent exchange of pouch young has been
observed in two cases, both at approximately the time young were first leaving the
pouch for short intervals.
Some females that mated while carrying a young in the pouch gave birth 6-11
days after permanent pouch exit of the primary young. Unmated females returned to
oestrus 12-24 days after permanent pouch exit of their young. Young were weaned at
2 5 3 ) months after pouch exit.
Most females entered anoestrus in 1968 following transfer of the animals into
small holding pens. In 1969 only 5 of 24 matings resulted in young in the pouch, while
in 1970 the corresponding figure was 21 of 44 matings. In both years there was evidence
of young being born but apparently being lost during the climb from the urogenital
opening to the pouch, probably because of overcrowding of the mothers.
Evolution of embryonic diapause is discussed in relation to the reproductive
pattern established for M. pavma. It is postulated that embryonic diapause first arose at
the end of pouch life and has come to occupy the entire length of pouch life in most
macropodids.