http://wiki.answers.com/Q/How_long_is_a_black_rhino_pregnant_for. A Black Rhino is pregnant usually between 419 and 478 days, or 15 to 16 months. The mother will give birth to a single calf, weighing in on average 35 to 50 kg, (about 80 pounds). The calf will stay with it's mother anywhere from 2 to 3 yea...