Kiwi North has farewelled one of its tuatara this week, a further blow after the death of a female kiwi last month.
Manager Allie Fry said the tuatara was found dead in its enclosure at the Kiwi House in Whangarei on Monday morning.
Specialist test results would determine the cause of death, which was unknown.
In April, a female kiwi, Kakari, had to be put down after a bird form of an ectopic pregnancy, Ms Fry said.
The autopsy showed she had internal problems, which meant she never would have survived the incident.