Two New Hoolock Gibbons born in Itanagar Zoo Two new Hoolock Gibbon babies were born in the Itanagar Zoo, increasing the number of Gibbons population to 19. The population of Hoolock Gibbons is around 1500 | 24 Dec 2020 6:22 AM GMT Itanagar: Itanagar Biological Park, popularly known as the Itanagar Zoo, has created another milestone with two Eastern Hoolock Gibbons (Hoolock leuconedys) born there within eight days, increasing the number of Hoolok Gibbons population to 19 and making the animal lovers of Arunachal Pradesh very happy. The first baby Hoolock was born to the zoo's youngest couple 'Jesu' and 'Sonu' on December 12 and the second to 'Bhat' and 'Yapa' on December 20, the biological park's veterinarian Dr Sorang Tadap looks after the health of the animals.