Proposed Flying-fox Relocation
For the last 20 years, Grey-headed Flying-foxes have camped in the Royal Botanic Gardens in Sydney, causing extensive damage to the heritage landscape and scientific plant collection. Prior to this occupation, it had been 70 years since the Sydney population of flying-foxes had last used this camp site.
In the 1990s the Botanic Gardens Trust used noise disturbance to reduce the numbers of flying-foxes in the botanic gardens, but when these measures were stopped in 2000, the flying-fox numbers continued to increase until they reached a maximum of 22,000 in the summer of 2008.
Six years ago the Royal Botanic Gardens in Melbourne successfully employed a more sophisticated noise disturbance program to relocate up to 30,000 Grey-headed Flying-foxes from their Fern Gully. The flying-foxes have remained in alternative camps and there were no reports of animals harmed during the relocation.
The Botanic Gardens Trust decided in 2006 that, to save the botanical collections and heritage landscape, the flying-foxes must be relocated using a program similar to that used in Melbourne. Experiences from the 1990s in Sydney indicated they were most likely to join other camps frequented by the Sydney population. However, contingencies are included in the relocation strategy to further relocate camps if they settle in unsuitable areas.
Flying-foxes are a protected native species and, as a result of population decline associated with habitat loss, are listed as ‘vulnerable’ under both State and Commonwealth legislation. For this reason, relocation must be approved by both jurisdictions.
Early in 2009, the Trust received conditional approval from the NSW Department of Environment & Climate Change for its plan to use noise disturbance to relocate Grey-headed Flying-foxes from the heritage-listed Royal Botanic Gardens to other camps in the Sydney area. The conditions were addressed and the relocation proposal was approved on 5 August 2009. The certificate of approval and approved documents are published below, in accordance with DECC conditions.
However, the Commonwealth Government requires the preparation of a Public Environment Report - a process which may take more than six months to complete - before they will consider final approval. The Botanic Gardens Trust has begun preparation of this Report, with the intention of relocating the flying-foxes in 2010 if approval is granted.
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Questions & Answers about the proposed relocation
- Why does the Botanic Gardens Trust want to move the flying-fox colony?
- The Flying-foxes have been there for years. Why is it so important to move them now?
- Why are the Botanic Gardens of ‘exceptional significance’?
- What is the scientific and heritage value of the tree collection?
- What type of damage do flying-foxes usually cause to trees/foliage etc.?
- Why are the Botanic Gardens so appealing to the Grey-headed Flying-foxes?
- When did the flying-foxes first start coming to the Gardens?
- How many flying-foxes currently reside at the Gardens?
- What is the process for the Botanic Gardens Trust to get approval to relocate the flying-foxes?
- How do you plan to move the flying-foxes from the Gardens?
- What is the basis of the relocation strategy? Why do you think it will work?
- Is the successful relocation of the flying-foxes from the Royal Botanic Gardens Melbourne a valid role model? The Melbourne camp was reasonably new (1985) and at the edge of the flying-fox known distribution, whilst the camp at the Royal Botanic Gardens in Sydney is long established with records of flying-foxes in the Gardens going back to the 1800s?
- How loud will the noise be? Will it affect nearby residents and businesses?
- What impact will the noise disturbance have on the welfare of the flying-foxes?
- Will the noise affect other wildlife in the Gardens? Will it drive away the birds as well?
- How long will the relocation take?
- When will the relocation take place?
- Will the public access to Sydney’s Royal Botanic Gardens be affected during the relocation?
- Where are the flying-foxes likely to go when they are relocated from the Royal Botanic Gardens?
- Will the damaged trees regenerate or is it too late?
- Will you just be moving the problem somewhere else? Won’t the areas to which the flying-foxes relocate also be in danger of being destroyed?
- What will you do if the flying-foxes go to new areas where they are unsafe or unwanted?
- How can you be sure the flying-foxes won’t just come back next season? Is this a permanent solution?
- How will the Botanic Gardens Trust encourage flying-foxes to feed but not roost?
- Who are the experts assisting with the proposed relocation?
- What is the estimated cost of the proposed relocation?
- Can’t the Botanic Gardens Trust plant more trees and provide a habitat for the flying-fox?
- Why don’t you just net the heritage trees to keep them out, like farmers do?
- Are people at risk from diseases spread by flying-foxes such as the Lyssavirus?
1. Why does the Botanic Gardens Trust want to move the flying-fox colony?
Roosting flying-foxes are killing significant trees and plants in the Royal Botanic Gardens.
Damage to trees from flying-foxes continues to be severe and widespread in the Palm Grove and rainforest areas in the centre of the Gardens, with more than 300 trees and palms (10 per cent of the collection) as well as the under-storey plants affected in some way. Eighteen trees have died and at least 135 trees have sustained serious damage to part or all of their canopies. Sydney tree expert, Judy Fakes, has advised us that heritage trees in the Palm Grove will continue to die unless we do something now.
As well as direct damage to the tall trees where the flying-foxes roost, palms in the lower canopy, some of which are rare or uncommon, are indirectly affected by sunburn from the loss of the upper canopy and having their fronds plastered with flying-fox guano.
This indirect impact has also caused a significant loss of under-story plants in the Palm Grove (e.g. a lot of wild sourced aroids collected from Malaysia and New Guinea have died).
The recent movement of the camp into the Australian Rainforest bed bordering the Palm Grove threatens more wild-sourced plants. Similarly, their movement into the traditional beds has resulted in the loss of wild species as well as hybrids and cultivars of begonias. Other beds outside the Palm Grove are being affected in the same way.
When the tall trees preferred for roosting are all gone, the flying-foxes will move of their own accord. By then the Gardens’ oldest trees and many other flora and rare specimens will have been destroyed along with the heritage landscape that they collectively create.
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2. The Flying-foxes have been there for years. Why is it so important to move them now?
Flying-foxes have always visited the Gardens at night to feed. However, in 1989, flying-foxes established a camp in the Gardens for roosting during the day, nearly 70 years after they last roosted there.
Extensive damage to the trees began when the numbers of flying-foxes rose from the low hundreds to thousands. During the peak in February 2008, there were 22,000 flying-foxes roosting in the Gardens. Even at their lowest numbers in winter, there are usually between 4000 and 7000.
Although a few hundred flying-foxes could live in the Gardens and cause minimal damage, these larger numbers in such a small area of tall trees are not sustainable. More significant trees will die and the beautiful landscapes will be destroyed.
The Botanic Gardens Trust wants to discourage flying-foxes from roosting in the day in the Gardens but not from feeding here at night.
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3. Why are the Botanic Gardens of ‘exceptional significance’?
The Royal Botanic Gardens Sydney Conservation Management Plan categorises the Gardens as an 'exceptional national cultural landscape'.
Historic significance: The site has been under continuous cultivation since European settlement in 1788 and a botanic garden since 1816. It contains the largest and most diverse continuously cultivated plant collection in Australia.
The overall form and content of the Gardens landscape as well as the organisation of the plant collections are the largely intact legacy of the early Directors of the Gardens, notably Charles Fraser, Richard and Allan Cunningham, Charles Moore and Joseph Maiden. Under these directors, living and preserved plant collections were acquired that have provided and continue to provide the foundation on which knowledge of Australian plants has been built.
The Gardens are a living museum showcasing almost two centuries of taxonomy and horticultural botany on Australian native plants, in particular rainforest trees of NSW and Queensland, Eucalyptus, and plants from the Sydney region.
South Pacific flora were also a subject of collection and study. The mid 19th century exploration and plant discovery in the South Pacific by Charles Moore is represented by a wide range of broadleaf evergreen trees, Palms, and southern Conifers in the Gardens. The latter includes type specimens of Agathis species (kauri pines) first studied and published in scientific literature by Moore and other scientists associated with the Gardens.
Throughout the 20th century, many distinguished scientists developed and codified knowledge and understanding of Australian plants using the plant acquisitions and research of these early botanical explorers and collectors.
Scientific significance: The Royal Botanic Gardens in Sydney holds an important and extensive collection of plants from all around the world. The extraordinary breadth of native and exotic plants were acquired over almost two centuries for the purpose of scientific study, including research for agriculture, ornamental horticulture and industry, and, more recently, conservation of biodiversity.
The organised study, classification and cultivation of the indigenous plants of New South Wales, Australia and the South Pacific region, remain core functions of the Gardens and associated National Herbarium of NSW, and are dependent on the living and preserved collections.
(See below, question 4, for further details of the scientific value of the tree collection.)
Social significance: The Royal Botanic Gardens attract four million visitors each year. They are greatly valued by the community and are used by a broad spectrum of people in diverse ways that include rest, recreation, health and fitness, socialising, celebration, education, artistic endeavour, and tourism.
From an early date the site developed a role of increasing the public appreciation and conservation of plants. It continues to perform this important educational function through displays, public lectures, tours and social and cultural events based on the living and preserved collections and the landscape setting.
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4. What is the scientific and heritage value of the tree collection?
The Royal Botanic Gardens in Sydney is recognised as holding one of the great tree collections of the world. The collection is a product of the early collection and study of Australian and South Pacific flora by Europeans and some species are now difficult to collect or rare in the wild.
The Palm Grove at the centre of the Gardens - and of the flying-fox camp - includes many of the oldest trees in the Gardens. There are 48 species of wild-collected palms available for scientific study or conservation. A number of these are rare in cultivation, e.g. Ceroxylon alpinum, Howea belmoreana X forsteriana, Jubaeopsis caffra, and Polyandrococos pectinatus. Our New Caledonian palms are particularly valued by the Palm and Cycad Societies of Australia.
Professor David Mabberley, in his contribution to the Conservation Management Plan for the Royal Botanic Gardens, identifies the collection of kauris in the Palm Grove and the rare palm, Pritchardia maideniana, as 'trees of international scientific and conservational significance'.
The Kauris, in particular, have been greatly affected by the flying-foxes and some significant specimens (including a specimen from the critical ‘type collection’ of Agathis moorei) have been killed.
These and many other trees provide representative specimens for scientific study by scientists at the Botanic Gardens Trust and elsewhere.
The living collections are a particularly rich resource for the study of plant taxonomy and classification (systematics). Plants grow in comparable conditions, their life cycle can be observed, their DNA extracted, their variability in form documented, and so on. Much of the recent research on plant evolution and new DNA bar-coding techniques has relied on samples from botanic garden collections. Several of our kauri pines, as well as trees in the Proteaceae family (which are from known wild origins and closely monitored and documented) were sampled. Our Tree Waratah, for example, was used for DNA extraction, dissection of flowers and studies of wood anatomy - all part of a worldwide study of the family Proteaceae.
Several fungal species have been discovered and described from palms in the Palm Grove so these specimens become what we call ‘type localities’ - important scientific reference points.
The trees and other plants in the living collections that are affected by the flying-foxes also have as yet untapped scientific uses. For example, Joinvillea, a bamboo-like plant growing in the Palm Grove was the focus of a recent study of floral development with the Jodrell Laboratory at Royal Botanic Gardens Kew. The Brown Silky Oak on the edge of the Palm Grove provided an accessible source of chromosomes for another project by Trust scientists.
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5. What type of damage do flying-foxes usually cause to trees/foliage etc.?
The weight and movement of large numbers of flying-foxes, particularly when they are roosting and breeding, can break branches and strip trees of leaves and new shoots. This damage weakens the tree, and with continued pressure, may eventually result in its death.
The dramatic loss of shade when the upper canopy of trees dies from roosting flying-foxes then damages or kills trees and plants underneath that are not suited to full sunlight.
Finally, large amounts of flying-fox guano kills the living tips of palms and other plants in the lower storeys.
The damage caused by the large concentration of flying-foxes living in the trees at the Royal Botanic Gardens is unsustainable.
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6. Why are the Botanic Gardens so appealing to the Grey-headed Flying-foxes?
Flying-foxes have lost a lot of their natural roosting and feeding habitat through changes in land use. The Gardens provide habitat, conveniently located near reliable food sources of nectar, pollen and fruits in street trees, suburban gardens, National Park and the Gardens themselves.
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7. When did the flying-foxes first start coming to the Gardens?
The flying-foxes have set up camp in the Royal Botanic Gardens at various times since Governor Macquarie had the foresight to set aside this land for a world class botanic garden in 1816. (They may have visited the area before European settlement, but the landscape and habitat were quite different.) Large numbers are recorded for 1858, 1900, 1916 and 1920 - in those times, flying-foxes were culled, something we wouldn’t contemplate today.
From 1920, there are no records of significant numbers in the Gardens for nearly 70 years. In 1989, 200 flying-foxes took up residence, growing to a peak of 3200 in 1992. Other urban camps in Sydney have similarly fluctuated in size over the years. The biggest concentration at the moment is at Ku-ring-gai Flying-fox Reserve in Gordon where camp size can reach more than 50,000 animals.
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8. How many flying-foxes currently reside at the Gardens?
Flying-foxes are migratory animals that move between camps so the numbers in the Gardens fluctuate dramatically, and are not necessarily the same individuals. There are generally fewer flying-foxes here over winter.
The 2008 peak was in February when numbers swelled to an estimated 22,000 which by August had dropped to less than 7,000 before escalating again.
The 2009 peak was in April with approx. 17,300 flying-foxes which by the end of June had dropped to around 5000–6000.
Fluctuations in numbers are believed to be related to flowering and fruiting of food trees in the area surrounding the camp. Flying-foxes will follow their food sources for hundreds of kilometres, stopping off at various camps along the way. The camps of Cabramatta and Gordon emptied completely in May 2009 and numbers dropped in other camps as up to 250,000 flying-foxes were reported near Batemans Bay on the South Coast where spotted gums (Corymbia maculata) were flowering.
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9. What is the process for the Botanic Gardens Trust to get approval to relocate the flying-foxes?
They Grey-headed Flying-fox is a protected native species and is listed as ‘vulnerable’ under the NSW Threatened Species Conservation Act of 1995 and under the Environment Protection and Biodiversity Conservation Act 1999. Their population decline is attributed primarily to habitat loss. Relocation must be approved by both State and Commonwealth governments.
At the State level, approval to relocate the flying-foxes is required under the NSW Threatened Species Conservation Act 1995 and at a federal level under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999.
Before undertaking the noise disturbance relocation program, application has to be made to the Director General, NSW Department of Environment & Climate Change, as well as to the Commonwealth Department of Environment, Water, Heritage & the Arts.
Approval has been granted by the NSW Government. However, the Commonwealth Government requires the preparation of a Public Environment Report – a process which may take more than six months to complete - before they will consider final approval. The Botanic Gardens Trust has begun preparation of this Report, with the intention of relocating the flying-foxes in 2010 if approval is granted.
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10. How do you plan to move the flying-foxes from the Gardens?
The Sydney relocation program will use a variety of mobile, moderate, and mainly percussive noises to disturb the sleeping patterns of the flying-foxes for ten minutes at hourly intervals during the day.
The noise will not be at a level that will frighten the flying-foxes into a panicked daytime exit and initially will only occur from noon, followed by a slightly higher level of similar disturbance to disperse them from the Gardens a little earlier than they would normally exit at dusk.
It is intended that the ‘bad hotel’ experience of interrupted sleep over days or weeks will eventually persuade the flying-foxes not to return from their nightly foraging but to seek less noisy camps.
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11. What is the basis of the relocation strategy? Why do you think it will work?
The relocation proposal has largely been based on the successful flying-fox relocation in 2003 by Royal Botanic Gardens Melbourne. Around 30,000 Grey-headed Flying-foxes were persuaded to decamp from the heritage-listed Gardens using a variety of intermittent daytime noises over a two-week period. The experiences from Sydney in the 1990s have also been useful in assessing the efficacy of noise disturbance, and the probable outcome of dispersal. No new camps were reported during the 90s, and the flying-foxes are most likely to join existing camps that are already familiar to them as part of their network of migratory stop-overs. However, any relocation will build in contingencies, similar to those used in Melbourne, to further relocate camps if they settle in unsuitable areas.
When the flying-foxes left the Melbourne Gardens, they were monitored to ensure that they did not roost at inappropriate sites. Most of the flying-foxes eventually settled at Yarra Bend, where the Gardens supported the establishment with interpretive signage, pathways, and a viewing platform overlooking the new flying-fox camp site. A small colony also established a camp at a new site in Geelong which has since been accepted by both the community and land managers. Throughout the relocation, there were no reports of any death or injury to a flying-fox as a result of the disturbance activities.
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12. Is the successful relocation of the flying-foxes from the Royal Botanic Gardens Melbourne a valid role model? The Melbourne camp was reasonably new (1985) and at the edge of the flying-fox known distribution, whilst the camp at the Royal Botanic Gardens in Sydney is long established with records of flying-foxes in the Gardens going back to the 1800s?
The current camp at the Royal Botanic Gardens Sydney was established in 1989 after almost 70 years absence - about five lifetimes of flying-foxes - so the age of the camp is similar to the camp that was dispersed from Melbourne’s Gardens. The Sydney camp is also a similar size to that camp.
In Melbourne there were no major camps closer than East Gippsland while in Sydney there are camps within the flying-foxes’ normal nightly flying range that, between them, could accommodate the population from the Royal Botanic Gardens. This may mean that relocation is relatively easy but so would be the return of the flying-foxes, for which reason we will be alert for the need to reintroduce the noise disturbance as part of an ongoing maintenance program.
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13. How loud will the noise be? Will it affect nearby residents and businesses?
The noise disturbance program will be carried out according to EPA noise regulations and in consultation with the City of Sydney. Nearby residents and businesses are not expected to be affected by the noise at these levels and in the centre of the Gardens.
Numerous sounds will be used, much of it recorded. We intend to begin the program using noise levels similar to those produced during every-day work in the Gardens by equipment such as chainsaws, hedge trimmers, tractors and bobcats. This noise, although common in the Gardens, will be produced more frequently than usual, and the noise will be aimed at the roosting flying-foxes.
Initially, the disturbance will take place for ten minutes each hour from noon to 4 pm, and just prior to dusk.
If different noise types are not eliciting the desired reaction of the flying-foxes, the noise level may be raised slightly and extended over a greater part of the day than noon to 4pm, in order to increase the effectiveness of the disturbance. However, in the Melbourne experience, the noise levels were actually able to be lowered after a while, as the flying-foxes became sensitised to the disturbance, so that much lower noise levels were able to disturb them.
If the flying-foxes need to be moved on from relocating to another inappropriate site, daytime and evening disturbance may be required at this site. This will only be done with the agreement of the local land owners/ managers and residents and if it is permitted by the Government licence conditions.
Throughout the relocation program, we will be consulting with nearby residents and local councils at any sites of disturbance to ensure that the disturbance to people is minimal.
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14. What impact will the noise disturbance have on the welfare of the flying-foxes?
A noise disturbance program, if approved, will meet all requirements of the licence issued under the legislation that protects threatened species.
The noise disturbance program used by the Botanic Gardens Trust in the 1990s proved to be very successful with no injuries or deaths to flying-foxes being attributed to the disturbance program.
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15. Will the noise affect other wildlife in the Gardens? Will it drive away the birds as well?
Wildlife such as ibises and possums share the Palm Grove with the flying-foxes. Wildlife that is active in the Gardens during the day move to other parts of the Gardens to avoid the noise of chainsaws, hedge trimmers, tractors, bobcats and a range of noise created by staff and visitors, later returning when the area is quiet.
Brush-tailed possums, which are extremely common in the Gardens, will be asleep in their hollows during the day, and are more likely to hide from the noise than try to run away. The flying-foxes are active at night so the noise disturbance is designed to interrupt their sleep cycle during the day, thus making the Gardens an unattractive place to roost.
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16. How long will the relocation take?
It is estimated that a concerted disturbance effort will take between two and four weeks to remove all the flying-foxes from the Gardens.
However our planning includes contingencies; if the flying-foxes land in unsuitable areas we need time to work with local land managers to move them on. This was done on several occasions in Melbourne’s successful relocation six years ago.
Therefore we have allowed 2-3 months for the relocation, even though we expect it to take less than 2 weeks for them to leave the Royal Botanic Gardens.
After we have relocated the flying-foxes we plan to maintain an ongoing vigil with dispersals, as necessary, during the evening and before dawn to discourage resettlement in the Gardens.
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17. When will the relocation take place?
State Government approval has been received but the relocation can only take place if and when approval from the Commonwealth Government is received.
Because of the further requirements of the Commonwealth Government (see Question 9) the earliest possible start date will now be May 2010. Flying-fox experts, veterinary scientists and conservationists on our steering committee have agreed that between May and July is the optimum time for relocation to avoid interrupting the flying-foxes’ mating season, separating mothers from their dependent young, or stressing heavily pregnant females.
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18. Will the public access to Sydney’s Royal Botanic Gardens be affected during the relocation?
To ensure public safety, access to the roosting areas in the centre of the Gardens will be restricted during disturbance activities. Signage will be placed at the gates and on the paths entering the roosting areas advising of access restrictions.
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19. Where are the flying-foxes likely to go when they are relocated from the Royal Botanic Gardens?
Flying-foxes are semi-nomadic animals that will travel hundreds of kilometres in response to flowering or fruiting food opportunities. They stop at various camps along the way, thus, there are no distinctive camps comprised of specific groups of individuals; rather a camp is a collection of animals that are roosting at the site at that particular time. Camps may be permanent, annual or irregular, depending on the reliability of food sources in the area.
It is expected the relocated flying-foxes will join existing camps around the Sydney metropolitan area. The fly-out directions of the flying-foxes seem to mainly be to the south and east, with some flying north over Port Jackson.
There are at least six existing flying-fox camps within a 50 kilometre distance of the Gardens, as well as five suitable potential National Parks sites within 20 kilometres that have been approved by the Parks and Wildlife Group.
The movements of the flying-foxes will be monitored after they leave the Royal Botanic Gardens to ensure they roost at appropriate sites. The Botanic Gardens Trust will seek feedback from local councils, rangers and the community about where the flying-foxes go following relocation efforts and work closely with land managers of existing and/or new sites.
If they set up camp in an unsuitable area, the Botanic Gardens Trust will work with local land managers to relocate them again, in accordance with the process used in Melbourne.
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20. Will the damaged trees regenerate or is it too late?
The postponement of the relocation for at least another year will have unavoidable impact, and will not allow the process of regeneration to begin. Our strategy will be to minimise damage.
Damage to trees from flying-foxes continues to be severe and widespread in the Palm Grove, restaurant, and rainforest areas, with more than 300 trees and palms (10 per cent of the collection) and understorey affected in some way. Eighteen trees have died and at least 135 trees have sustained serious damage to part or all of their canopies.
Constant defoliation and the inability of the trees to successfully produce new foliage means that the trees will be relying on stored sugar reserves. As many of these plants are mature and thus storing fewer sugars, this additional load on their system may make them more susceptible to invasion by secondary pathogens that may enter through the wounded branches. This impact is cumulative.
Our practice of retaining dead wood in the canopies of trees colonised by the flying-foxes has reduced the impact on the living sections of the trees. However, this results in a visually degraded landscape and is another risk management issue as dead wood is more likely to fall onto paths and other parts of the living collection.
This year, several of the old trees will need to have the dead wood removed for safety reasons. This will have the effect of removing roosting habitat, sending the bats onto other branches and trees, resulting in further damage.
More positively, relatively high rainfall and continuing good tree care over the last few years has improved the prognosis for some trees. Of the handful of trees earmarked for removal a year ago, all but one are still alive.
Netting of a few of the most endangered trees is likely to be amongst the tactics introduced this year to help save the trees until the flying-fox relocation is possible.
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21. Will you just be moving the problem somewhere else? Won’t the areas to which the flying-foxes relocate also be in danger of being destroyed?
Wherever the flying-foxes go, we will consult with the land managers to determine whether or not the site is an appropriate roosting site for the flying-foxes, whether the site is physically able to sustain the flying-foxes and whether it is acceptable to the local community. If it is determined that the new site is likely to suffer unacceptable levels of damage or be in conflict with the local community’s needs, we will commit to moving the flying-foxes on to a more suitable location for as long as is permitted under the relevant licences.
The best outcome will be for the camp to disperse amongst existing campsites and/or the approved new sites in the National Parks without overcrowding any one campsite.
The relocation is necessary to save Sydney’s Royal Botanic Gardens and the relocation program proposed is the only solution to a complex problem.
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22. What will you do if the flying-foxes go to new areas where they are unsafe or unwanted?
We will work with land managers and implement disturbance programs to move them on from unsuitable locations to suitable ones - this was done successfully when flying-foxes were relocated from the Royal Botanic Gardens Melbourne.
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23. How can you be sure the flying-foxes won’t just come back next season? Is this a permanent solution?
If the initial disturbance is successful at relocating the flying-foxes from the Gardens, we will monitor the trees daily. At the first sign of any further roosting by the flying-foxes in the Gardens, we will recommence the noise disturbance in order to prevent the numbers from building up to unsustainable levels again.
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24. How will the Botanic Gardens Trust encourage flying-foxes to feed but not roost?
Noise disturbance will not be conducted during the night-time foraging period. This will allow the flying-foxes freedom to feed wherever they choose. The Gardens offer a considerable range of fruits and flowers year round.
Following an initial successful dispersal of the flying-fox camp in 1992, a further 200-300 were successfully discouraged on two other occasions. The flying-foxes did not roost but were observed to feed in the Gardens.
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25. Who are the experts assisting with the proposed relocation?
Our steering committee consists of representatives of the RSPCA, NSW Wildlife Council, NSW Department of Environment & Climate Change, Ku-ring-gai Bat Conservation Society, Ku-ring-gai Council, Cabramatta Creek Flying-fox Committee, Wolli Creek Preservation Society, Parramatta Park Trust, Centennial Parklands, Fairfield City Council, Sydney University (including biologists specialising in flying-foxes), the Botanic Gardens Trust, Friends of The Gardens, and the Royal Botanic Gardens Melbourne.
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26. What is the estimated cost of the proposed relocation?
After a few false starts, the operations of the Melbourne relocation cost about $250,000. Our initial advice was that it would cost about half that - a small price for even one of our heritage trees. Given the delays and time spent on applications, that cost will be higher but the Trust is committed to saving the Royal Botanic Gardens collections and will provide whatever resources are required.
A financial assessment of the damage the flying-foxes cause and the cost of the long-term repair of the Gardens would be many times than is spent on this relocation. It is near impossible to put a price on the irreplaceable heritage, scientific and aesthetic value of trees that have been lost and will be lost if nothing is done.
Staff will be assisted by volunteers, and the provision of monitoring, research and management support for existing and/or new flying-fox camps are also included in the budget.
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27. Can’t the Botanic Gardens Trust plant more trees and provide a habitat for the flying-foxes?
The landscape of the Royal Botanic Gardens itself is considered to be of heritage importance and the composition and design of the Royal Botanic Gardens is carefully planned to maintain its heritage value. The design, plant content and variety have the primary purpose of providing key plant related messages through landscape displays and the use of interpretative information. For educational and aesthetic purposes, many plantings are grouped according to scientific, geographical, evolutionary, aesthetic and horticultural history criteria.
Any new plantings take a long time to mature, and with many of our most significant tree specimens now dying, we do not have time to wait. Our thematic plantings may not even suit the requirements of a flying-fox colony, even when they have matured, as they are designed with the purpose of maintaining the heritage, plant science, and aesthetic values of the Gardens in line with our Conservation Management Plan, rather than recreating habitat for wildlife.
Even if an area of new plantings or artificial roosts could be established in time and in keeping with the mission of the Botanic Gardens Trust, discouraging flying-foxes from trees that they have colonised to a new adjacent area would be much harder than keeping them out of the Gardens totally (our experiences under current licences in trying to protect individual trees have been largely unsuccessful).
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28. Why don’t you just net the heritage trees to keep them out, like farmers do?
In orchards, trees are a uniform height (usually no more than 5 m) and planted in straight rows. In the Royal Botanic Gardens netting would need to accommodate the tallest affected trees which are 30 m tall and would have to cover the entire Palm Grove as well as adjoining garden beds, otherwise the colony would simply move from the netted areas into the un-netted areas. Netting the entire area would be very expensive and not in keeping with the landscape values of the 192-year-old botanic garden. Furthermore, the flying foxes would still need to relocate to a new habitat so the end result would be the same as using noise disturbance.
As a short-term solution, given we are unable to relocate the flying-foxes this year, a few individual specimens at risk may be netted to nurse them through another year.
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29. Are people at risk from diseases spread by flying-foxes such as the Lyssavirus?
The risk of a person catching any disease from a flying-fox is minimal. Although large numbers of flying-foxes have roosted at the Royal Botanic Gardens for almost 20 years there has never been any reported serious injuries or illnesses caused by these flying-foxes.
However the Australian Bat Lyssavirus (ABL), is deadly to humans as well as bats, so it is important to take precautions. This disease is believed to be carried in a very small proportion of the flying-fox population, and can be transmitted to humans through a bite or a scratch. Flying-foxes are generally quite docile animals. The best precaution is to make no attempt at handling a flying-fox unless you are appropriately trained and vaccinated. If you find one in distress, call WIRES 13 000 WIRES or 1300 094 737or Sydney Wildlife 02 9413 4300.
Although, there is no known risk of disease transmission through flying-fox urine or faeces, in cases where flying-foxes leave behind a mess on your property, basic hygiene/cleaning practices are recommended, e.g. washing any outdoor food preparation surfaces with an appropriate cleaning solution, and cleaning with water any walking surfaces that may present a slip hazard.
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