Zoo adds to tuatara population

A rare 5-month-old Cuvier Island tuatara is dwarfed by Zeus, an Auckland Zoo tuatara from the Stanley Island group, who is approximately 80 years old. Picture / Greg Bowker

A population of rare tuatara has been given a boost with the birth of 15 youngsters at Auckland Zoo.

The rare Cuvier Island tuatara hatched from a clutch laid at the zoo in November, boosting the sub-species' numbers to 48.

Auckland Zoo first received six adult tuatara from Cuvier Island, off the Coromandel Peninsula, in 1990.

To date, the zoo has bred and released 18 juvenile tuatara back onto the 202ha island.

When breeding the reptiles, Victoria University scientist Dr Nicola Nelson aimed to produce more males - by controlling the temperature at which the eggs were incubated - because too many females had hatched previously. However, the sex of the tuatara won't be known until they are older.

The 15 youngsters, now aged between three and five months, will be kept out of the public eye at the zoo for the first six months.

It will take between four and five years for the tuatara to grow to about 80g (they now weigh just under 10g) so they can be released on to Cuvier Island - big enough not to be preyed on by adult tuatara.

Tuatara - Maori for "spiny back" - have barely changed since they walked with the dinosaurs 225 million years ago.