Wild populations of the critically endangered species have slowly swelled from a dismal fewer than 50 birds six years ago, to about 140 birds.

This year will be the fourth in a row that more than 100 orange-bellied parrots naturally migrate north from their breeding grounds in Tasmania.

The Mainland Release Trial is behind the bolstered numbers, with the program since 2017 releasing more than 120 orange-bellied parrots into Victoria.

The birds have joined other wild orange-bellied parrots once released.

In the seventh and final year of the state's trial, another 19 birds from Zoos Victoria along with the Tasmanian Department of Natural Resources and Environment have been released at Lake Connewarre, southeast of Geelong.

Animal experts generally lose track of the birds, but that won't be an issue as they trial a system called ATLAS, which stands for Advanced Tracking and Localisation of Animals in real life Systems.

It's the first time researchers in Australia have used the system, which includes a fixed receiver station along with the radio transmitters to tell them how birds use their habitats.

ATLAS will help researchers from Zoos Victoria and Deakin University trialling the system to gather data on where the orange-bellied parrots are in Victoria.

"This is the first time this tracking technology has been used in Australia," Deakin University terrestrial ecology Professor Don Driscoll said.

"It pinpoints all the parrots every eight seconds and gives us an amazing insight into which parts of the habitat they are using and what they use it for."

The tracking technology will allow researchers to determine how to best protect the orange-bellied parrot from extinction, Zoos Victoria senior manager Michael Magrath said.

Environment Minister Ingrid Stitt announced the 19 birds' release on Saturday.

She lauded the growth of the parrots' wild populations and said it was fantastic future generations could enjoy the species.

Australian Associated Press