A routine check up of the bilbies recently found two of the females have produced joeys.

The zoo's sanctuary is located behind-the-scenes in Dubbo. It's used for the conservation breeding programs of the greater bilby and the plains-wanderer.

Taronga Recovery and Conservation Programs manager Andrew Elphinstone said it was really exciting to see two of the five females released into the sanctuary in October had a single pouch young.

"The fact the greater bilbies have produced offspring so quickly after being released into the sanctuary demonstrates they have adapted extremely well to their new home," Mr Elphinstone said.

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Greater bilbies can have up to three pouch young at a time, although one or two joeys is more common.

Gestation lasts for 12 to 14 days and then the joey will stay in a mother's pouch for 75 to 80 days. About two weeks after leaving the pouch the bilbies are independent.

A second cohort of the bilbies has already been released into the sanctuary, bringing the total number to 15. More will join them in 2020.

"Over the next 12 months we'll have a third cohort of bilbies go into the sanctuary and we'll also be doing some larger scale population estimates so hopefully we'll see significant growth in our bilby population," Mr Elphinstone said.

"Like everyone at the moment though we're really being challenged by this drought. But hopefully come next spring there's a lot more bilbies on the ground."

It's hoped the second cohort of bilbies will start breeding in the near future.

"Overall we couldn't be happier with the first two months post-release. It has taken years to get to this point," Mr Elphinstone said.

"To have breeding success and healthy bilbies is a testament to the team working behind-the-scenes to ensure this program is a success."

During the routine check, the bilbies were assessed to ensure they're thriving in their new environment and their tracking devices were changed.

"We're really happy with how the bilbies have settled in. They have established burrows and and are in good health and body condition, so they are definitely doing well in their new habitat," Mr Elphinstone.

Initial GPS tracking data shows the bilbies are traversing large distances across the 110 hectare sanctuary on a weekly basis.

The breeding program is dedicated to ensuing the long-term survival of the species.