Bombing from above
The other night, after dinner in Parliament, I went for a quick walk around the Botanic Gardens at the back of Parliament. That counts for 5000 paces towards my 10,000 a day for cardiovascular health. I had been in meetings all day without a break – not even for lunch – and we would be sitting in debate until 2:30 am. I needed fresh air.
As I walked, a continuous stream of thousands of flying foxes flew overhead from north to south. They were like allied bombers crossing the English Channel towards Dresden. The foxes were also bombing, a constant stream of white acidic wet excreta. The old explorers used to say, “never sleep under a spreading Moreton Bay fig”. They knew why.
The nightly migration from the caves at Ku-ring-gai to the figs of Central Park, the Domain, Hyde Park and other places is a remarkable sight as tens of thousands pass overhead in a straight line. Flying foxes are large bats, weighing up to 1 kg, with a wingspan which may exceed one metre.
They sleep all day and feed all night on pollen, nectar and fruit. In their faeces are seeds of whatever fruit they have been eating. This means a wide dispersal of future trees. Small seeds are often swallowed and may not pass through the gut until up to one hour later, by which time flying foxes could be 35-50 km away from the tree from which the seed came.
By dispersing rainforest seeds over wide areas, flying foxes give seeds a chance to grow away from the parent plant, and potentially expand remnant patches of valuable rainforest vegetation. It is estimated that a single flying fox can dispense up to 60,000 seeds in one night.
Flying foxes, otherwise known as fruit bats, are mammals with the largest body size of all bats. Their wings are translucent, thin and rubbery. Most around Sydney belong to the uniquely Australian Grey-headed Flying-fox family. Their head and back are covered with coarse hair and their faces are similar to a rat. Strangely for such a large population they are an endangered species. There are also in Sydney Black Flying-foxes found usually in the tropics.
Fruit-eating flying foxes (known as mega-bats) use sight and smell to find their food. Their vision is just as good as ours during the day and even better at night. For the first three weeks after birth, the females carry their dependent young with them on their foraging flights. By the age of around five to six months, the young should be fully weaned and foraging with the adults. They are relatively long-lived mammals with the average age of reproductive animals between six and ten years. Sexual maturity is reached after two to three years.
There is a large colony of tens of thousands in the caves at Ku-ring-gai National Park. Then there are also safe ‘permanent’ camps, where flying foxes regularly roost, occupying them all the year round. Flying foxes are very sociable and because they are so focused on finding food in many different locations at night, they use ‘camps’ for social contact (as well as for rest) when they are all together during the day.
But at dusk, flying foxes depart from their camps to feed on various local food resources. As dawn approaches, they gradually start to return to the camp from which they came, whereas others may fly to another nearby camp to rest for the day.
Through pollination and seed dispersal, flying foxes help to provide habitat for other flora and fauna species and also help to sustain Australia’s hardwood timber, honey and native plant industries. But to be effective in this role, flying foxes need to be in large numbers.
The problem is that these camps may be in areas of special interest to humans, such as The Royal Botanic Gardens Sydney. The bats can do an enormous amount of damage to historic and heritage listed tree specimens that are of priceless cultural, scientific, horticultural and educational value.
In the Botanic Gardens are an estimated 22,000 flying foxes, that eat continuously, mess continuously and roost continuously, killing many trees and damaging scores of others; 18 trees of significance have been lost and more than 300 plants damaged in the last few years. In order to save the botanic collections and the heritage landscape, the Botanic Gardens Trust is proposing to relocate the flying-fox camp to other camps in the Sydney metropolitan area, using methods adapted from the successful relocation of a camp of Grey-headed Flying foxes from the Royal Botanic Gardens, Melbourne.
If you want to make any comment about this, contact the Royal Botanic Gardens before 5 pm on Wednesday 23 December 2009. I do not know where they will be relocated, or the method to be used. In rural areas permits for shooting them can be obtained, and loud noise generators in paddocks are designed to frighten them away.
But the nightly flights are a great tourist attraction, and I saw a number of people the other night taking photos with mobile phones and expensive cameras. But one word for the wise –walk quickly from underneath the flight path or else you will be bombed from above!
Rev the Hon. Dr Gordon Moyes AC MLC