Perth Zoo has celebrated the birth of another Goodfellow's Tree Kangaroo.

Haroli was the size of a jellybean back in July 2016, but is now starting to become noticeable - he follows the arrival of Mian who was the first Tree Kangaroo to be born at the Zoo in 36 years.

"Haroli and Mian are half-brothers, both fathered by 'Huli who came to Perth Zoo from Queensland in 2015 after being identified as the best genetic match for the breeding program," said fauna keeper Kerry Pickles.

"Mother Doba is a first time mum and is very cautious with her joey who has been keeping his head out of the pouch more frequently."