Staff at Washington`s National Zoo is perplexed and in mourning over the death of a second adult male gorilla in the past three days.
Saturday, a male named Kuja died as veterinary surgeons tried to implant a device similar to a pacemaker to improve the functioning of his failing heart.
After his death, it was decided to introduce the other adult, named Mopie, into the family group of gorillas, as groups without males tend to experience social problems, zoo spokeswoman Peper Long told the Washington Post.
Like Kuja, 460-pound Mopie also had cardiomyopathy, a heart condition that is a leading cause of death among captive male gorillas, but Long said staff hadn`t seen any indications his condition had reached the stage of heart failure.
Soon after his introduction into the group on Monday, 'he collapsed and died,' Long said.
She said results of the autopsy could take several weeks to be finalized.
The zoo`s only surviving male gorillas are young brothers Kwame, 6, and Kojo, 4.