"Discovery of a chick is another sign the habitat is suitable for kiwi. They are making themselves at home."
Late last year, staff who had been tracking the birds believed at least two couples had formed.
Mr Peat, who has written three books on kiwis, said the ecosanctuary would like to build the largest satellite population outside the birds' natural range, in the mountains south of Haast.
"We've been advised that Orokonui could sustain about 30 breeding pairs, and eventually some of the progeny, surplus to the breeding population here, will be returned to the South Westland mountains when they are old enough and large enough to withstand predators."
In support of the recovery of the species, the ecosanctuary would be liaising with DoC and the iwi guardians, Te Runanga o Makaawhio, over the return of Orokonui-hatched birds in the future.