Ecology andManagement ofFlying Fox Camps inan Urbanising Region

Flying foxes are important pollinatorsand seed dispersers of many plantspecies. They play important roles inthe reproduction, regeneration anddispersal of plants within rainforests,eucalypt forests, woodlands andwetlands. During the day, flying foxesroost in communal camps, whichprovide them with a protectedenvironment and a place to socialiseand safely rear their young. ‘Traditional’campsites can be used for decades. Insome cases, cities and towns have beenbuilt near the sites of traditional flyingfox camps, while in other cases flyingfoxes have moved into urban areas andformed new camps. Within urban areas,flying fox camps can pose a nuisancefor nearby residents.To help manage flying fox camps inurban areas, the factors that influencethe location of camps were studied insoutheast Queensland, the fastestgrowing urban area within Australia. Thisstudy found that most flying fox campsin southeast Queensland are locatedclose to waterways in the coastallowlands – the same zone that isintensively used for urban development.Even within this zone, flying foxes showa preference for locating their campswithin patches of suitable vegetationsurrounded by urban areas, rather thanin extensive forest. Flying fox campsitesoccur in a range of vegetation types,but most comprise tall trees with a denseunderstorey, or are located in swampsor mangroves. At the local scale, theremay be some potential for managingvegetation to alter its use by flying foxes,either to deter them from occupyingcertain areas or to provide new areasof suitable habitat.

ISSUE 5 JUNE 2006

Issues in Tropical Forest Landscapes

Ecology andManagement ofFlying Fox Camps inan Urbanising Region

A flying fox camp within a remnant patch of rainforest.

distances, sometimes up tohundreds of kilometres.Nevertheless, they still display stronglinks to ‘traditional’ campsites. Forexample, a number of campsitesdescribed in the 1930s are still

occupied today. Flying foxesoccasionally establish newcampsites, often as a result of thedestruction or severe disturbanceof traditional camps, or harassmentof the flying foxes within them.

Ecology and BehaviourFlying foxes roost in largecommunal camps, often withinpatches of dense vegetation (e.g.rainforest, paperbark swamps ormangroves). These roost sitesprovide shelter, focal points forsocial interactions and secureplaces to rear young.

Camps may be occupied on apermanent or seasonal basis, andcan support hundreds to tens ofthousands of individuals. Thenumber of flying foxes in a campcan vary at different times of theyear, and from one year to thenext. In southeast Queensland,grey-headed and black flying foxesare the regular occupants ofcamps, often occurring together.Camp populations can swellgreatly with irregular influxes of littlered flying foxes. Over a period ofdays, individual flying foxes maymove between different camps ina local region. Over longer periodsthey are known to travel larger

Flying Foxes of Southeast Queensland

Species and Their DistributionThree species of flying fox occur in southeast Queensland – the grey-headed flying fox (Pteropus poliocephalus), theblack flying fox (P. alecto) and the little red flying fox (P. scapulatus). All are large bats that feed at night on fruit andblossom and roost during the day in communal camps.

Grey-headed flying fox• Occurs in eastern Australia,

primarily in coastal lowlands.• Listed as Vulnerable by the

Commonwealth, New SouthWales and VictorianGovernments.

Black flying fox• Widespread across coastal

tropical and sub-tropicalAustralia.

• Also occurs in New Guinea andIndonesia.

Little red flying fox• Widespread across northern

and eastern Australia.• Also occurs in New Guinea.

Species is nomadic; populationsfollow blossoms.

In northeast Queensland, the grey-headed flying fox is replaced by the spectacled flying fox, P. conspicillatus, whichalso occurs in New Guinea and Indonesia.

An aerial photograph of a flying fox camp, circled, in the Gold Coast region of southeast Queensland.

Human Interactions withFlying FoxesFlying foxes provide a number of‘ecological services’ that benefithumans, including pollinating nativeplants and dispersing their seeds.In some places, the spectacularfly-outs of bats from their campsitessupport a growing ecotourismindustry.

On the other hand, flying foxes cancause considerable damage tocommercial fruit crops, which hasresulted in their persecution,particularly in rural areas. Farmersand fruit growers use a range ofmethods to prevent flying foxesfrom raiding orchards, withexclusion netting being an effectivetechnique.

People living near flying fox campsin urban areas may find the odour,noise, droppings and raids onbackyard fruit trees a nuisance.Roosting activities can also causeconsiderable damage to thevegetation at camp sites,particularly when camps arelocated within small patches ofvegetation.

Like other wild animals, some flyingfoxes may carry diseases that canbe transmitted to humans.Recently, Australian Bat Lyssaviruswas identified in some bats.Infection in humans is extremely

At night, flying foxes navigateprincipally by sight. Their excellentsense of smell helps them to locatefood. They feed mainly on blossomand fruit from a wide variety of plantspecies, including the flowers ofeucalypts and melaleucas(paperbarks). Flying foxes canmigrate long distances to followthe mass flowering of eucalyptsand related plants. Sources of fruitinclude areas of rainforest as wellas planted trees in residential andagricultural areas. Large native figtrees may be especially important.The little red flying fox has a morespecialised diet, feeding mainly onnectar and pollen.

unlikely as the virus can only betransmitted through direct contactwith an infected bat that results ina bite or scratch. If you comeacross a sick or injured bat, contactyour local wildlife carer or your Parksand Wildlife Service for advice.Only people who have beenvaccinated against the virus shouldhandle bats. For more informationon bat lyssavirus, searchQueensland Health website(www.health.qld.gov.au).

Location andCharacteristics of FlyingFox Camps in SoutheastQueenslandTo guide the management of flyingfox camps in the rapidly urbanisingregion of southeast Queensland(SEQ), researchers of the RainforestCRC and Griffith University haveworked to identify the factors thatinfluence their location. Fortycamps were in use by grey-headedand black flying foxes within SEQat the time of the study (2005).Twenty camps were ‘regularlyused’, that is, they were occupiedfrequently and had supported largepopulations (more than twothousand individuals) of flying foxesfor most years over the previousdecade. The remaining campswere used sporadically or

Flying foxes play important rolesas pollinators and seed dispersersin native forests.

Flying foxes use sound tocommunicate with each other.Their camps are noisiest at dawnand dusk as individuals arrive orprepare to leave. Calls duringdaylight hours occur mainly duringthe mating season or in responseto disturbances. Males produce ascent to mark their territories, whichcontributes to the characteristicsmell of flying fox camps.

Flying foxes live for up to fifteenyears in the wild. Females reachmaturity at two to three years ofage, and produce only oneoffspring per year. In grey-headedand black flying foxes, births occurbetween September andNovember. Young are raised forthree to four months after whichthey become independent. Littlered flying foxes give birth in Apriland May.

supported fewer flying foxes.Grey-headed and black flying foxesoften used the same camps.

Records kept by flying foxresearchers show that the numbersof flying foxes in SEQ camps canvary greatly, both in space andtime. For example, over the lastdecade, numbers of grey-headedflying foxes in each of the SEQcamps have ranged from twentyto eighteen thousand individuals,while numbers of black flying foxeshave ranged from zero to twelvethousand individuals. Thesepatterns probably reflect themovement of flying foxes in searchof food resources.

Figure 1: The location offlying fox camps insoutheast Queensland,shown in relation tosurrounding woodyvegetation (green) andurban land (grey). Redtriangles represent‘regular’ camps; yellowdots represent othercamps.

vegetation in which the camp waslocated, distance to other flying foxcamps, composition of neighbouringplant communities and the amountof surrounding urban land andwoody vegetation. Since flyingfoxes are highly mobile,measurements of the latter factorswere made at the ‘landscapescale’ (mostly a 2-10 kilometreradius) around each site.Comparisons of campsites withrandom points showed that flyingfox camps were preferentiallylocated:• In coastal lowland areas (eighty

percent of campsites in SEQwere less than sixty metresabove sea level);

• In close proximity to a river, creekor other drainage line (all withintwo hundred metres); and

• In a patch of woody vegetationat least one hectare in size.

Only eighteen of the forty campsitesin SEQ occurred in areas of intactnative vegetation (as defined by theQueensland EnvironmentalProtection Agency), includingmangroves, rainforest and sclerophyllforest. The majority of campsoccurred in small or disturbedpatches of native vegetation andregrowth, often containing manyintroduced trees and shrubs.

Landscape ScaleAttributes of Flying FoxCampsResearchers measured theenvironmental attributes of flyingfox camps and compared thesewith the characteristics of randomlychosen sites to test whether campswere associated with particularattributes. At each site, factorsthought to be important to flyingfoxes were measured, includingelevation, distance to nearestwaterway, size of the patch of

Figure 2: Analysis of land cover surrounding flying fox camps in the lowlands of southeast Queensland. The graphs show the proportionof flying fox camps (light blue bars, n = 40) and random sites (dark red bars, n = 50) surrounded by different amounts of woody vegetation

and urban land within a two-kilometre radius. Camps tended to be surrounded by less woody vegetation and more urban land thanrandom sites. Similar trends were evident in analyses of cover within five and ten kilometres of camps, although the negative association

of camps with woody vegetation cover was not significant at the ten-kilometre scale.

Flying foxes often camp in patches of tall trees with a dense understorey.

To determine whether flying foxcamps were preferentiallyassociated with particularlandscapes in the coastal lowlands,further analyses were conductedwith random sites constrained tothe coastal lowlands within twohundred metres of water and inpatches of vegetation more thanone hectare in size. This analysisfound that, even in the coastallowlands, flying fox camps tendedto be surrounded by land in which:• Urban development was

common, e.g. two thirds ofcamps, but less than tenpercent of random sites, weresurrounded by more than threesquare kilometres of urban landwithin a two kilometre radius;and

• Woody vegetation wasuncommon, e.g. seventypercent of random sites, butonly forty percent of camps,were situated in areas whichhad more than four squarekilometres of woody vegetationwithin a two kilometre radius).

Camps used regularly by flying foxeswere surrounded, on average, bytwice the amount of urban landwhen compared to the lessregularly used camps.

There are several possible (but nottested) reasons why flying foxesmay prefer to camp in urban areas.First, many trees that have beenplanted in streets, gardens and parksprovide food for flying foxes. Forexample, flying foxes feed on thefruits of fig trees and the nectar ofeucalypts throughout urban areas. Furthermore, these trees may fruit

and flower reliably in urban areasbecause of frequent watering andfertile (or fertilised) soils. Second,well-lit features of urban areas suchas roads and other infrastructuremay provide flying foxes withnavigational cues. Third, thepersecution of flying foxes in ruralareas by humans may have led tothe establishment of some campsin cities.

The tendency for flying fox campsto be located in areas with relativelylow woody vegetation cover doesnot mean that native forests arenot important for flying foxes. Flyingfoxes can forage large distancesfrom camps (often up to twentykilometres) and could potentiallycamp and forage in different partsof the landscape.

Pro

port

ion

of s

ites

Pro

port

ion

of s

ites

FURTHER READING

Eby, P. and Lunney, D. (eds) (2002) Managing theGrey-headed Flying Fox as a Threatened Speciesin New South Wales. Royal Zoological Society ofNSW, Mosman, NSW.Hall, L. S. and Richards, G. (2000) Flying Foxes:Fruit and Blossom Bats of Australia. University ofNew South Wales Press, Sydney.Markus, N. and Hall, L. S. (2004) Foraging behaviourof the black flying fox (Pteropus alecto) in theurban landscape of Brisbane, Queensland. WildlifeResearch 31, 1-11.Roberts, B. (2005) Habitat characteristics of flyingfox camps in south-east Queensland. BSc. (Hons.)Thesis, Griffith University, Brisbane.

ACKNOWLEDGEMENTSThis paper was prepared by Billie Roberts,John Kanowski, and Carla Catterall of the RainforestCRC and Environmental Sciences, Griffith University,with support from a Griffith University CommunityPartnerships grant and the Queensland Parks andWildlife Service. We acknowledge the assistanceof Brett Kerr, Peggy Eby, Les Hall, Shannon Hoganand Gail Spina, and the contributions of a largenumber of naturalists and flying fox enthusiastswho supplied information on roosting habits andlocations. Data in Figures 1 and 2 from SLATS(Department of Natural Resources and Mines2003). Photographs courtesy of Vivien Jones.

Centre for InnovativeConservation StrategiesGriffith UniversityTelephone (07) 3735 5394Facsimile (07) 3735 5014Email CICS@griffith.edu.auwww.griffith.edu.au/centre/cics

CRC ResearchTelephone (07) 4042 1246Facsimile (07) 4042 1247Email rainforestcrc@jcu.edu.auwww.rainforest-crc.jcu.edu.au

CONTACTS

Queensland Parks andWildlife ServiceTelephone 1300 130 372Email csc@epa.qld.gov.auwww.epa.qld.gov.au

Local Scale Attributes of Flying FoxCamps

The vegetation structure andcomposition of eighteen ‘regularlyused’ flying fox camps wereexamined in detail. The attributesassessed included the density ofwoody stems, foliage cover, heightof the vegetation, and the heightand species of roost trees.

Flying fox camps were generallylocated in tall trees (more than tenmetres high). The trees used forroosting usually grew above adense understorey of small treesand shrubs, except where thecampsites were subject to periodicinundation by surface water (e.g.Melaleuca swamps andmangroves). There was littleevidence of selection for particulartree species or types of trees forroosting.

Some recently established camps(less than twenty years old)occurred in areas where all nativevegetation other than someeucalypt trees had once beencleared for pasture. In these sites,the removal of stock had alloweda dense understorey to develop,often composed of introducedshrubs. Flying foxes may prefer thistype of habitat because it providesthem with a variety of roostlocations, including cool positionson hot days and sunny, shelteredpositions on cold days. The denseunderstorey may also providesome protection from disturbancefrom land-based animals andhumans.

ManagementImplicationsThe location of flying fox campsmay depend on a range of factorsincluding:• A suitable climate;• Access to abundant and

reliable food and waterresources;

• The availability of roost sites thatoffer favourable microclimatesor protection from land-basedpredators; and

• Proximity to rivers, roads andother ‘navigational aids’.

In a rapidly urbanising landscape,many of these factors may changeover time (e.g. with thedevelopment of new suburbs),altering the suitability of particularcampsites for flying foxes.

There are some ways in which theimpacts of flying fox camps onsuburban residents might bereduced, such as through thecreation of new campsites awayfrom residential areas or by alteringthe suitability of existing campsites. A number of attempts have beenmade to relocate urban flying foxcamps in Australia, however, manyhave been unsuccessful and allhave been costly. Over $2 millionwas spent removing a flying foxcamp from Melbourne’s RoyalBotanic Gardens in 2003.

The results of this study suggest someguidelines for the creation of flyingfox campsites in southeastQueensland. Potential newcampsites would need to belocated in lowland areas within twohundred metres of a waterway,and be at least several hectares insize to allow the colony to movearound the patch over time.Campsites developed onpreviously cleared land wouldneed to include a mix of tallemergent trees and a denseunderstorey. Alternatively, a denseshrubby understorey could beestablished beneath existing tall,scattered trees.

Measures aimed at deterring flyingfoxes from occupying parts of acamp near residential areas couldinclude removing the lowerbranches of trees and clearing theunderstorey, to create a bufferbetween roosting animals andsurrounding residents. Such actionswould need to be undertakencarefully, preferably in conjunctionwith the extension or creation ofsuitable habitat elsewhere, andsubject to a monitoring program.

Further research into the factorsinfluencing the establishment andpersistence of flying fox camps isrequired to help solve conflictsbetween flying foxes and humansin urban areas.

2070

cix.

com

.au