Why are flying-foxes important?
Flying-foxes are native to Australia and make a significant contribution to maintaining healthy ecosystems as essential pollinators and seed dispersers for native forests.
In turn, these forests provide valuable timber, act as carbon sinks, stabilise our river systems and water catchments, and promote recreation and tourism opportunities returning millions of dollars to our economy each year.
Pollen sticks to the flying-foxes’ furry bodies and as they crawl from flower to flower, and fly from tree to tree, they pollinate the flowers and aid in the production of honey.
Eucalypts rely heavily on these pollinators, producing most of their nectar and pollen at night to coincide with the time when flying-foxes are active.
Because flying-foxes are highly mobile, seeds can be moved locally and over great distances. When seeds are able to germinate away from their parent plant, they can have a greater chance of surviving and growing into a mature plant.
Seed dispersal also expands the gene pool within forests. Mature trees then share their genes with neighbouring trees of the same species and this transfer strengthens forests against environmental changes.
This reinforces the gene pool and health of native forests.
Flying-foxes are an important part of the diet of some native predators, including the powerful owl Ninox strenua, the largest native owl of Australia and a vulnerable species under Queensland’s legislation. Research shows flying-foxes comprised almost half of the total weight of food consumed by a pair of powerful owls.
Why do flying-foxes now roost in certain areas?
Flying-foxes are highly mobile nocturnal animals that need access to sources of flowering and fruiting trees to sustain their large roosts. They are capable of travelling up to 50 km each night between their roost site and places where their food is available.
They leave at dusk and use their well-developed sense of smell to find known feeding sites or search for new ones.
They respond to changes in food availability by either foraging in different areas or moving to a different roost site closer to food sources.
The use of roost sites varies—some roosts are permanently occupied, others are used less frequently, and roosting may even occur at a site not previously recorded as a roost.
Sometimes for reasons not understood, a roost may move a short distance of a couple of hundred metres.
Roosts are typically located near waterways on coastal lowlands, more likely to occur in small patches of bushland near urban development than in large patches of bushland.
Consequently, roosts often occur close to residential areas. Given the amount of bushland that has been cleared for development, flying-foxes are likely to have less available roost sites than they once did.
It is hard to predict how long a roost will be occupied. The size of an existing roost will often swell for a few weeks or months with the arrival of other groups of flying-foxes, especially the highly mobile little-red flying-fox.
Why is it important that flying-foxes aren’t disturbed?
The current occurrence of Hendra virus is an important consideration in flying-fox management and the department works closely with Biosecurity Queensland and Queensland Health when assessing damage mitigation permit applications to disperse flying-foxes.
Attempting to move a flying-fox roost could increase the Hendra virus load in those flying-foxes and also spread the virus into other areas.
If flying-foxes are impacting on the health and wellbeing of the public or causing damage in a community, landowners or councils can apply to the department for a damage mitigation permit (DMP) to safely manage a roost.
When assessing a DMP application, a range of matters are considered including human health and wellbeing and the likely effects on the survival of the animals in the wild.
Any consideration to disperse a flying-fox roost will be based on a comprehensive assessment of the situation. The dispersal and relocation of a flying-fox roost will only be considered if an alternative roosting site is available.
A DMP may be granted to a landholder or a local authority to disperse flying-foxes by non-lethal means in an effort to move them to a new location.
Illegally disturbing flying-foxes in a roost; driving them from a roost; interfering with their roost; or harming or killing flying-foxes without a DMP can attract penalties of up to a $100,000 fine or up to one year's imprisonment.
How far can a flying-fox travel?
A flying-fox is a highly mobile nocturnal animal that need access to sources of flowering and fruiting trees. As each species of tree only flowers and fruits for a limited time, flying-foxes must search for new food sources regularly. Little red flying-foxes are well known for their mass migrations forming temporary roosts of hundreds of thousands of animals as they fly thousands of kilometres each year following the seasonal flowerings of native trees.
Individual grey-headed flying-foxes have been recorded travelling more than 2000 km over a nine month period with nightly foraging trips of up to 50 km. As part of another study, black flying-foxes were tracked by satellite crossing 150 km of open water to reach Papua New Guinea from Cape York on four different occasions.
What if flying-foxes live nearby?
From a public health perspective there is in almost all circumstances no reason for a community to be alarmed if a colony moves in nearby.
In 1996, Australian bat lyssavirus (ABL) was identified in flying-foxes. However ABL is not a reason to fear flying-foxes as it is very rare and preventable. ABL can only be transmitted to humans when infected flying-fox saliva comes into contact with human tissue through an open wound or with mucus membrane, e.g. eyes, nose and mouth. Therefore it is very important that flying-foxes are not handled by members of the public.
Humans are not exposed to ABL if flying-foxes fly overhead or feed or roost in gardens. Nor is it spread through droppings or urine, or if you live, play or walk near their colonies.
While there is understandably community concern about the current Hendra virus outbreak, it is important to remember that such outbreaks are rare and occur in exceptional circumstances only.
There is also no evidence that humans can catch the virus directly from flying-foxes.
There is a proper process in place where the department can work with members of the public, local authorities and other organisations to manage flying-foxes where difficulties arise.
Why are flying-foxes roosting where people live?
Roosts are typically located in forest with a canopy height of more than five metres near waterways on coastal lowlands, and often in small patches of bushland near urban development.
As coastal areas are usually developed for human settlement, roosts often occur close to residential areas. Given the amount of bushland that has been cleared for development, flying-foxes are likely to have fewer options for roost sites than they once did.
How long will flying-foxes roost in the one place?
It’s hard to predict how long a roost will be occupied. The size of an existing roost will often swell for a few weeks or months with the arrival of other groups of flying-foxes, or abruptly move a few hundred metres for a short period and even move back to its original location.
Recent research has also shown that individual flying-foxes will move hundreds of kilometres and take up residence in established roosts.
Roost sites may be permanent or temporary and occasionally a colony will move to a site where flying-foxes have never been recorded before.
Will living near flying foxes harm my health?
Flying-foxes along with many other animals can carry and transmit viruses to other species of animals. Of most concern to human health is their ability to transmit Australian Bat Lyssavirus (ABL) to humans and Hendra virus to horses. ABL is transferred through bat saliva coming into contact with an open wound (e.g. when bitten or scratched) or mucous membrane tissue such as the eyes or lining of the mouth or nose. Hendra virus is believed to be transmitted to horses when they eat grass or fodder that an infected flying-fox has contaminated with saliva, urine or birth products. If the horse is infected it can transmit the virus to other horses and humans. There is no indication that humans can catch the virus directly from flying-foxes.
One person tragically died from ABL transmitted by a flying-fox in 1998 and since that time any suspected exposure has been effectively treated through a post-exposure vaccination. There have been four fatalities from Hendra virus being transmitted by infected horses.
Transmission of these viruses only occurs as a result of close contact with infected animals. Avoid contact with flying-foxes and protect horse food from contamination by flying-foxes.
You are not exposed to these viruses if flying-foxes fly overhead or feed or roost in your garden, or if you live, play or walk near their colonies.
Why so noisy?
When at a roost or feeding, flying-foxes ‘squabble’ loudly. This mixture of screeches and cackles is actually communication and allows them to establish personal roost sites or feeding territories, ward off rivals, communicate with their offspring, and warn others of possible threats. The grey-headed flying-fox is known to have more than 30 specific calls. By listening and watching, it may be possible to link some of a flying-fox's behaviour to the calls it makes.
Why the smell, noise and mess?
Flying-foxes communicate through a series of calls and use scent to identify themselves and their territories within a roost. Their smell is not from their droppings or urine.
The mess from their droppings is the combined result of the flying-fox’s liquid, high energy diet of nectar and soft fruit pulp, and their rapid digestion (less than 30 minutes)—both adaptations that help keep the animal light enough to fly.
Little can be done to alleviate these problems other than to take what ever steps possible to block out the noise and smell and wait for the flying-foxes to move on. The mess made by flying-fox droppings is mostly concentrated around feeding trees and roost sites. In these areas cars and washing should be covered at night and walls and other exposed surfaces cleaned as regularly as possible to avoid paint damage.
Why are flying-foxes so hard to scare off?
Flying-foxes remember the locations of roost sites and often retain strong attachments to them; revisiting them when seasonal food sources become available nearby.
The same flying-foxes do not stay in a particular roost. Satellite tracking shows that individual animals or groups constantly move from roost to roost, sometimes every few days. While roost sites can be permanent, individual flying-foxes can move freely between them at any time.
Therefore roost sites act as a network of ‘home bases’ which flying-foxes rely on for safety, ready access to food, and places to mate and raise their young. This fundamental reliance on roosts for survival means that flying-foxes are unlikely to abandon them and will resist attempts to scare them away.
Dispersal of a flying-fox roost is rarely successful and is only considered as a last option for managing a situation where they are causing an economic impact or affecting human health and wellbeing.
Flying-foxes are protected under the Nature Conservation Act 1992 and it is illegal to disturb or attempt to relocate them without the appropriate authority (i.e. a damage mitigation permit) issued by the department. Damage mitigation permits (DMPs) are issued subject to a number of conditions to ensure that any plan to disperse a flying-fox roost doesn’t impact on the survival of the flying-foxes. The main condition is that a flying-fox roost can only be relocated if there is an alternative roost site that the animals can move to. Nor can a roost be dispersed if flying-foxes are about to give birth or have newborn young as any disturbance at these times may cause females to abort, or their dependent young to become separated and fall to the ground and die.
Disturbing flying-foxes is also likely to place the animals under additional stress. Where there is a concern that the flying-foxes are carrying Australian Bat Lyssavirus or Hendra virus, additional stress on the animals could have the undesirable effect of increasing the spread of the virus within the roost population and further affect the health of individual animals. Disturbing flying-foxes while they are feeding or roosting could therefore contribute to a disease risk rather than remove it.
Can flying-foxes be culled?
Flying-foxes are protected species by law. Because they are highly mobile and can occur in many areas of Queensland, it is impractical to try and cull them.
Species found in Queensland are also found in other Australian states and territories, and in countries north of Australia, including Papua New Guinea and Indonesia. Attempts to reduce flying-fox numbers in Queensland may result in flying-fox groups arriving from other areas to fill the ecological vacancy.
Harming or attempting to harm a flying-fox without a DMP is an offence and penalties apply.