It is also plausible to say that X. grandis do not produce young every year.

There is a single report of a female producing young asexually.

They usually produce one young per birth, after a gestation of 152-155 days.

Females will often not produce young if food is scarce.

Females experience estrus again about a month after producing young.

All Roman women of suitable age were commanded to marry and, if possible, produce young.

In order to produce young there had to be two individuals in co-operation.

If that happens, they would no longer be able to produce viable young.

In west Germany, around 80% of nests before the 1950s produced young, but only 54% were successful in the 1960s and '70s.

Conditions, both for male and female, had to be absolutely perfect to produce young.