Leopards - Depending on the region, leopards may mate all year round. In Manchuria and Siberia, they mate during January and February. The estrous cycle lasts about 46 days and the female usually is in heat for 6–7 days. Gestation lasts for 90 to 105 days. Cubs are usually born in a litter of 2–4 cubs. But mortality of cubs is estimated at 41–50% during the first year.