A litter of five cheetah cubs born in May at the National Zoo's Smithsonian Conservation Biology Institute near Front Royal have aced their first medical exams.

One of the five cheetah cubs at the Smithsonian Conservation Biology Institute, in a photo taken June 14. (Adrienne Crosier, Smithsonian Conservation Biology Institute )

Crosier said there is a 20 percent mortality rate among cheetahs during their first six months, so biologists will keep a close eye on their health.

It is the third litter born at the institute since the cheetah facility opened in 2007.

There are now 16 cheetahs at the institute, one of eight cheetah breeding centers in North America.

The cubs' mother is 6-year-old Amani, and their father is 3-year-old Sorris.