Rhino Moms only give birth to one Tot at a time. It takes about 15 months of pregnancy to deliver 100 pounds of Tot. One is a plenty big assignment, both before and after birth.
So all Rhino Tots are ‘only children’ while they are with Mom (2 or 3 years). Later, Mom may have another, but usually the maturing sibling is off to attend to other business.
The Dads are on their way 15 months ago. That’s how We do it.