DURHAM (WTVD) --Researchers at the popular Lemur Center at Duke University are trying to figure out what caused the mysterious deaths of four endangered lemurs.
Two males and two female aye-ayes ranging in age from 7 to 28 years were stricken suddenly and died within 24 hours.
There are fewer than 50 aye-ayes in captivity in the entire world.
"We had 13 and now we have nine," said Andrea Katz, the Lemur Center's animal curator. "This is the most significant loss we've ever had and is a terrible blow to our breeding program. This is a significant percentage of the aye-ayes in the U.S. at this time."
There are 250 other lemurs at Duke, and so far no other animal has shown signs of illness.