Author Rachel Carson’s dystopian vision of a silent spring is rapidly being realised, according to a global survey which pays particular attention to our falling bird populations in Tasmania.
The report on the state of the world’s birds reveals a biodiversity crisis largely driven by land clearance and intensive farming, with once-common species now at risk.
One in eight bird species is threatened with global extinction, says the State of the World’s Birds report, a five-year compendium of population data from the best-studied group of animals on the planet.
In all, 74 per cent of 1469 globally threatened species – out of about 10,000 total bird species in the world – are affected primarily by farming. Logging, invasive species and hunting are the other main threats.
And no more is this threat more apparent than in Tasmania. We have four critically endangered species which breed here, two of them migratory parrots. One of the rarest birds in the world – the orange-bellied parrot – was down to just 19 wild birds at the start of the last breeding season and there will be a nervous wait in early September to see how many of these, and their offspring, arrive back at their breeding grounds in the south-west wilderness from wintering areas along the Victorian coast. The loss of saltmarsh feeding areas – which are rapidly being drained and developed in industrial and agricultural projects – have been a major factor in its demise.
Although the swift parrot has not yet reached the extremely low numbers of the orange-bellied parrot, there are grave fears for its survival in the future. Its population, which numbers a little less than 1000 pairs, is being impacted by the clearing of its favoured blue gum habitat and predation in is nesting hollows by sugar gliders, an animal not native to Tasmania which was introduced as a pet in the 1800s.
Two other species facing extinction in the state are the King Island thornbill and the King Island scrubtit, which are down to a mere handful of individuals. These birds, though, are sub-species of healthy populations that remain common on the Tasmanian mainland.
Australia-wide, at least 20 bird species are in danger of extinction in the next 20 years, to join the 29 species which have vanished in the 200 years since the start of European settlement.
Across the world, Birdlife International says in the report: “Each time we undertake this assessment we see slightly more species at risk of extinction – the situation is deteriorating and the trends are intensifying.”
According to the report, at least 40 per cent of species worldwide are in decline. After farming, logging is a key factor in declines of 50 per cent of the most globally endangered species, followed by invasive species (39%), hunting and trapping (35%), climate change (33%) and residential and commercial development (28%).
Even at sea birds are not safe, with overfishing, long-line fishing practices and climate change affecting seabird species like the wandering and royal albatrosses which are getting less common in Tasmanian waters.