the silence of the birds

Java, Indonesia – the world's most populous island, home to 135 Million people. "Originally Javan wildlife supported a rich biodiversity" but there's no hint of seeing just one animal nowadays, expect at the bird market. Javan rhinoceros and Javan leopard are extinct and not one of the 450 bird species could be heard singing. Do they hide? Is this a clue to their evolution to survive? How do the children grow up without the co-existence of animals and their voices? Such a silence was too bizarre.