As if dying honey bees in America weren’t bad enough, now another major pollinator, fruit bats, also known as flying foxes, are dropping dead in Australia. The largest of bats, the fruit bat is one of the most important to humans. They disperse the seeds and pollinate the flowers of many of the fruits and vegetables that we consume including bananas, peaches, dates, carob, avocados, jack fruit, plantains, mango, guava, cashews and figs, as well as rainforest flora and eucalyptus trees. According to an Agence France-Presse report, scorching temperatures resulting from climate change have caused the deaths of thousands of Australian bats. In January 2002, as many as 3500 bats, 6% of the fruit bats in nine colonies in New South Wales, died in just one day as temperatures rose over 42 degrees Celsius (107.5 F).
British and Australian researchers, led by Justin Welbergen of Cambridge University, described what they observed among the bats behavior on that day in January in a paper published with the Proceedings of the Royal Society. First, the bats sought shade and began wing fanning in an attempt to cool off. Within a couple of hours the flying foxes were panting and drooling saliva. Finally, individual animals began falling from trees, dying within 10 – 20 minutes. The New South Wales Threatened Species Conservation Act has listed two of the species most affected by high temperatures as “vulnerable”; the black flying foxes, which lost up to 13 per cent of their population in New South Wales and Queensland during the heat waves and grey-headed flying foxes, which suffered 24,500 deaths and are thought to have a population of just 400,000 left in the world.
Found to be most susceptible overall are females and young bats, with mortality rates of young bats as high as 50% in the effected colonies. This is likely to adversely affect the breeding of bats and, in turn, the species of plants and ecosystems that are reliant upon them for seeding and pollination.
Concurrently, thousands of fruit bats are also dying from a paralysis tick epidemic in north Queensland, which may also be tied to climate related events. Last March, Cyclone Larry felled a great number of trees, causing the bats to feed on the wild tobacco which sprang up in place of the trees and grows at ground level, exposing them to the ticks. The bats habitats are also under threat from human expansion and they are sometimes killed by humans for being “pests”, with farmers complaining of bats eating their cultivated fruit.
Scientists estimate that, in total, more than 30,000 Australian fruit bats have died from heat waves since 1994. Thousands more have died from other causes. This has potentially devastating impacts on agriculture and ecosystems in Australia and is another indication that climate change on the driest continent must be addressed immediately.