The hope of takahē chicks in the Tararua district has been dashed.
The first eggs in 20 years to be laid at Pukaha Mount Bruce Wildlife Centre is infertile.
Rangers are disappointed as they went to extra efforts to keep breeding pair Natural and Fomi's egg safe.
"Pukaha ranger, Jess Flamy, checked the takahē nest this morning and confirmed there was not one egg laid but two," the centre said in a statement.
"It was also confirmed that neither egg held a chick."
Staff remain hopeful a fertile egg is laid in future.
"Pukaha Mount Bruce's very first conservation breeding programme was with the takahē and dates back to the late 1960s," said conservation manager Todd Jenkinson.
"These takahē eggs at Pukaha are still a symbol of the full circle of takahē breeding at Pukaha. We are hopeful that the pair will give it another go."
Takahē have in recent years have made a remarkable recovery from the brink of extinction, with the number of birds tripling in three decades.