The story of a seabird translocation to Mana Island, involving fluffy white-faced storm petrel chicks, artificial burrows and sardine smoothies.

'Bringing back the seabirds' is the rallying call for conservationists working to restore Wellington's Mana Island.

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The latest seabird to be brought back to Mana Island is one of New Zealand's smallest - the white-faced storm petrel.

A handful of these sparrow-sized birds already breed on the island, and the Friends of Mana Island are hoping the 260 chicks they have rehomed to the island in the past three years will soon give this number a welcome boost.

The new arrivals hail from Rangitira, in the Chathams, which is home to a thriving white-faced storm petrel breeding population.

They were collected as late stage chicks, and translocated to Mana Island via crayfish boat, plane and helicopter.

Upon arrival, each chick was fed and transferred to an artificial burrow. The burrow comprises a dark, quiet nesting chamber with a soft floor of dry leaves.

A tunnel made from drainage coil gives access to the world outside, although for the first few days the chicks are barricaded inside to prevent them wandering outside and getting lost.

A team of volunteers from the Friends of Mana Island, led by seabird expert Cathy Mitchell, look after the chicks for several weeks until they develop their full adult plumage and are ready to fledge.

Once a day, each chick is collected from its burrow and taken to the classic caravan that serves as the dining room.

The chick is weighed to check that it is on a perfect trajectory - adding precious grams until the final week before departure, when it needs to slim down to flight weight.

A wing measurement gives an indication of flight readiness - wing feathers grow up to 3 mm a day until they are about 50 mm long.

Health and Plunket check complete, Cathy and sidekick Shane Cotter give each bird its once daily meal - 7 ml of sardine smoothie delivered directly into the crop via a syringe and a soft feeding tube.

A sardine smoothie - made from finely blended sardines, fish oil, boiled water and a vitamin pill - mimics the natural diet of krill that parent birds feed their sole chick once a day.

Once Cathy judges that a chick is getting close to departure, the barricades on its tunnel come down. Then, if the chick is so inclined, it can explore down the tunnel during the night and check the outside world.

Depending on the chick, this stage might last a few days until one night it will leave the burrow and without any fanfare, simply lift off and fly away…

Go to this episode on rnz.co.nz for more details