October 27, 2017 Latest News No Comments
Grey-headed flying-foxes hanging out; they like to socialise. Photo by Vivien Jones

Grey-headed flying-foxes hanging out; they like to socialise. Photo by Vivien Jones

Residents of Kingfisher Street in Albany Creek, Brisbane, have demanded that Council again disperses a local camp of flying-foxes. While we understand the potential problem of living near flying-foxes, Wildlife Queensland wishes to balance the argument with greater awareness of the species’ role and the challenges faced when dispersing them.

Kingfisher Street in Brisbane’s north is currently home to 2,450 flying-foxes (1,960 grey-headed and 490 black) according to monitoring carried out on 10 October 2017 by Moreton Bay Regional Council (MBRC). Given that flying-foxes can congregate in camps of over 1 million individuals, the camp on Kingfisher St is considered to be relatively small.

MBRC records also show that this flying-fox population has been declining since August 2017. Once recorded to have 4,300 flying-foxes, the area is currently home to only 2,450. MBRC data also reflect the species’ nomadic nature, recording that flying-fox numbers in the area are constantly fluctuating as the animals move to other camps, just as they have been recorded doing in other places such as Esk, Canungra and Logan.

This is not the first time MBRC has taken action to disperse the flying-foxes of Kingfisher St. Back in 2016 a dispersal event took the numbers to below 500. However, as demonstrated by the current and increasing population of flying-foxes in the area, this management technique has not been successful.

Nor was it successful in the case of the Royal Botanic Gardens in Victoria where $3 million was spent on the dispersal of a camp of 30,000 flying-foxes, only to have their presence persist and two new camps form within a 6.5km radius.

Flying-foxes as a species provide a very important service to many Australian ecosystems. Their roles as flower pollinators and seed dispersers provide benefits to a variety of native flora, making them more important than ever as numbers of insects such as bees performing similar tasks decline.

Flying-foxes feed primarily on nectar, fruit and flower blossoms of Australia’s native vegetation. Eucalypts, among other plants, are a favoured source of food for many flying-foxes. In turn, eucalypts rely heavily on flying-foxes for cross-pollination which improves their gene pools. During foraging periods flying-foxes disperse seeds either after the seed is passed through the gut or when it is dropped elsewhere due to competition for food. These activities result in seeds moving further distances from the parent plant. This improves the gene pool of the plant which in turn improves its likelihood of adaptation. Flower pollination is achieved in much the same way.

For these services to be successful however, flying-foxes must exist in large numbers. Larger numbers create competition for food which encourages further seed dispersal. Coupling the decline in flying-foxes in Australia with the decline in bees will certainly mean a loss of native Australian plants, such as the iconic eucalyptus.

Though clearly important to the ecosystem it cannot be argued that flying-foxes don’t cause a great deal of disturbance to local residents due to the noise and smell associated with large camps. Due to this, local Councils are authorised to undertake non-lethal dispersal as a management technique to control flying-fox camps. Dispersal events occur with the use of fog, helicopters, lights, noise, physical deterrents, odour, smoke, ultrasonic sound, removal of vegetation and water, and birdfrite. Other techniques such as creating more attractive habitats for the camps have also been tried to encourage flying-foxes to move elsewhere. However, many dispersal events throughout Queensland have resulted in failure to move the camps on. A review by Roberts and Eby (2013) of flying-fox dispersal events stated that 16 out of 17 cases did not reduce the number of flying-foxes in the local area. And if the animals did move, they did not move far, causing problems for a larger number of local residents.

Further, dispersal events are difficult to control as it cannot be predicted where the flying-fox camps will disperse too. In Bundall 1,600 black and grey-headed flying-foxes were part of a dispersal event which consisted of removal of extensive vegetation. As a result, the flying-foxes did not leave the area, nor did the local population reduce in size. It was believed two new camps had formed, however, six camps were within a 5km radius.

Wildlife Queensland would like to state that dispersal of flying-foxes during breeding or birthing season will cause detrimental impacts on the species’ existence. At this time of year the species requires stability as October/November is when the black and grey-headed flying-foxes give birth and rear young. As we have already seen the grey-headed flying-fox decline by 30 percent in the past 15 years, this season is particularly essential to their survival.

Wildlife Queensland would also like to clarify the perceived health risk associated with flying-foxes. Often, the broader community perceives flying-foxes as a danger to the health of local residents; however, this is not the case. Though flying-foxes do carry diseases such as Hendra Virus and Australian Bat Lyssavirus (ABL), Hendra Virus cannot be passed directly from flying-foxes to humans (horses contract the virus from flying-foxes and can then pass the disease to humans) and ABL can only be passed to humans if an infected individual bites or scratches a human. These risks are both very low. In the last 20 years three people have died of ABL and four people are known to have died of Hendra virus. When compared with other statistics (in 2015, 12 people died of lightning strikes in New South Wales) flying-fox related fatalities are very unlikely.

And finally, let’s not forget we’re the reason that species such as the black flying-fox are moving into urban areas. Humans continue to clear natural flying-fox habitat for activities such as agriculture, urban development and mining, reducing the number of foraging and roosting trees and forcing flying-foxes to adapt to urban environments.

 

Roberts B and Eby P 2013, ‘Review of past flying-fox dispersal actions between 1990-2013’ The Australian Bat Society Inc.

Written by Wildlifeqld