Grey-headed Flying-fox Management Strategy for the Lower Hunter Grey-headed Flying-fox



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Table 7.2The Lower Hunter

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The Grey-headed Flying-fox

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Table 10.1General Ecology

10.1.1Taxonomy

Order: Chiroptera

Suborder: Megachiroptera

Family: Pteropodidae

Genus: Pteropus

Species in NSW: Pteropus poliocephalus (Grey-headed Flying-fox; refer to Plate 4.1)
10.1.2Conservation Status

The GHFF is protected under the following legislation:



  • in NSW under the NPW Act (administered by OEH);

  • in Victoria under the Flora and Fauna Guarantee Act 1988 (administered by Department of Sustainability and Environment);

  • in Queensland under the Nature Conservation Act 1992 (administered by Department of Environment and Heritage Protection); and

  • in South Australia under the National Parks and Wildlife Act 1972 (administered by SA Department of Environment Water and Natural Resources).

Additionally, the GHFF is listed as a species of conservation concern as follows:



  • Vulnerable within NSW under the NSW Government TSC Act (administered by OEH);

  • Vulnerable within Victoria under the Victorian Government Flora and Fauna Guarantee Act 1988 (administered by the Victorian Department of Sustainability and Environment);

  • Vulnerable across Australia under the Commonwealth EPBC Act (administered by DSEWPaC); and

  • Vulnerable Internationally (IUCN Red List).

Identified nationally as a ‘Vulnerable’ species, the GHFF is facing a high risk of extinction in the wild in the medium-term future (Duncan et al 1999). The reasons (criteria) that qualify the GHFF for this category include population reduction of over 20% over the last three generations, actual or potential levels of exploitation and effects of introduced taxa, hybridisation, pathogens, pollutants, competitors or parasites (Duncan et al. 1999). Since 1989, further evidence shows a decline in numbers of the GHFF of 30% (Tidemann et al. 1999, Parry-Jones 2000, Eby & Lunney 2006, NSW Scientific Committee 2001). The long-term population decline of the GHFF is considered greater than this. Ratcliffe (1932) hypothesised a 50% reduction in Australian flying-fox numbers had occurred by the late 1920s. The major threats affecting the GHFF have been identified as loss of foraging and roosting habitat, culling associated with orchard management and resource competition with the Black Flying-fox, Pteropus alecto (DECCW 2009a, NSW Scientific Committee 2001).




      1. Distribution

GHFFs are endemic to Australia, distributed throughout coastal lowlands and ranges of eastern Australian from Mackay, Queensland in the north (Roberts et al. 2008), through NSW, to Melbourne, Victoria in the south (Menkhorst 1995, Roberts et al. 2012a). Since 2010, the range of the GHFF has extended to Adelaide (DEWNR 2012). In 2010, small camps were also established in other areas that were previously rarely used, such as Orange (Cenwest Environmental Services 2010), Young and Bathurst in western NSW, the Albury / Wodonga NSW / Victorian border area and Bendigo in Victoria. The Lower Hunter Valley is therefore close to the centre of the geographical range of the GHFF.
The GHFF is a highly mobile, migratory species that relies on food sources which have largely irregular patterns of productivity (Eby & Law 2008, DECCW 2009a). Some individuals migrate whereas others are sedentary (Fleming & Eby 2003, Tidemann & Nelson 2004). The migratory characteristics of individuals vary widely. Continuously occupied camps located in floristically-diverse landscapes or urban areas contain small resident populations. Some members of the migratory population show seasonal fidelity to camps, with regular patterns of occupation, while others are largely nomadic, following more erratic pulses of nectar (Eby 1991 & 1996, Parry-Jones & Augee 2001, Fleming & Eby 2003, Tidemann & Nelson 2004, Roberts et al. 2012b).
Reasons for undertaking long-distance movements may include access to additional foraging opportunities, search for mating opportunities, exchange of information about other parts of the range, and / or a combination of these (Tidemann & Nelson 2004). Patterns of movement vary markedly between individuals in terms of distances travelled and time spent at different roosts, within and between regions (Roberts et al. 2012b). Most long-distance movements involve latitudinal (north–south) shifts and cover a significant part of the species’ geographical range, which spans approximately 2,000 km from northern to southern limits (Roberts et al. 2012a), although its range extends to Adelaide along the southern coastal fringe.
Studies indicate the species is panmitic (Eby 1991, Webb & Tidemann 1996) and, as such, all GHFF must be regarded as one continuous population. This is a significant factor for the management of this species.


      1. Habitat

10.1.2.1Roosting Habitat

GHFFs are highly colonial, roosting in canopy vegetation in aggregations often referred to as ‘camps’. Typical characteristics of flying-fox roosting habitat (Eby 2002, Eby & Lunney 2002, Hall & Richards 2000, Peacock 2004, Roberts 2005) include:



  • closed canopy (rainforest, mangroves, floodplain or riparian forest dominated by Eucalypts, Corymbia, Casuarina spp. or Melaleuca quinquenervia);

  • continuous canopy area >1 ha (ideally >10 ha in size);

  • within 50 km of the coast or at elevation <65 m;

  • close proximity to waterways (<500 m), commonly rivers or creeks;

  • level topography, <5o incline;

  • canopy height >8 m; and

  • positioned within nightly commuting distance (generally <20 km) of sufficient food resources to support the population of a communal roost.

These characteristics alone cannot predict where GHFF choose to camp and additional characteristics such as microhabitat traits, features of the surrounding landscape or simply the logistical location may also be important. Camps occur in vegetation ranging from continuous forest to remnants as small as 1 ha (Eby 2002, West 2002), although camps in vegetation smaller than this also occur (e.g. Lorn – approximately 0.2 ha). Urban roosts can be located in public parks in areas with continuous canopy cover (ARCUE 2009) or even in sites where canopies are relatively separate. In many cases, roosts in park lands do not contain a well developed understorey, often comprising of tall tree specimens with a mown or manicured grassy understorey (e.g. Lorn in Maitland and Burdett Park in Singleton). Landscape features near roosts, such as river and creek systems, may assist flying-foxes to navigate, as may street lighting in urban landscapes (Birt et al. 2000).


The locations of camps are generally stable through time, with approximately 250 camps having been recorded within the range of the GHFF (Eby 2008). In NSW, only 5% of these roost sites occur in conservation reserves (NSW Scientific Committee 2001). At any time, the majority of camps are empty, however flying-fox numbers can quickly increase to >20,000. Camps vary in their patterns of occupation from sites occupied infrequently and for short periods, to sites that are occupied on a continuous basis (DECC 2009a). Eby (2008) notes that camps associated with rainforest fruits and highly diverse flower-producing forests show more consistent patterns than camps associated with less-complex vegetation. Flying-foxes have well-developed spatial memories, enabling individuals to remember the locations of camps (Roberts 2009), even those occupied very infrequently (Eby 2008).
There is evidence that the stability of roost locations has diminished in recent years. New camps have been established in several local areas, and various long-established sites have been abandoned to be replaced by new sites in relatively close proximity (Birt et al. 2000, Hall 2002, Smith 2008, Roberts et al. 2011, Eby et al. 2012 and unpublished data). Changes in roosting patterns are often attributed to disturbance of existing sites and altered conditions experienced during food shortages, although other unknown conditions may also contribute. Dispersal actions at long-established camps generally result in both the establishment of a new, replacement site and fragmentation of the local population such that the number of camps in a local area increases (Roberts et al. 2011). Flying-foxes establish new campsites during periods of food shortage, some of which persist once environmental conditions improve (Smith 2008, Eby et al. 2012 and unpublished data). Some of these camps are established in areas outside the previously recognised range of GHFF, such as Adelaide and Canberra. However, the majority occur in previously occupied areas. In these circumstances, an increase in the density of camps provides the opportunity for flying-foxes to reduce their foraging distances and energy requirements and also possibly to reduce competition for resources.
10.1.2.2Feeding Habitat

At night, flying-foxes navigate principally by sight (rather than echolocation as is the case with microbats), with their sense of smell and spatial memory assisting them to locate food. GHFFs forage up to 50 km from camps, although >75% of foraging activity is within a 20 km radius (Eby 1991, Tidemann 1999). The feeding distances of resident animals are shorter than those in the migratory population (Eby 1996). GHFFs have adapted to cleared and highly-altered landscapes, and there is no evidence that habitat responses, particularly avoidance of disturbed areas, influence feeding flights (Eby 1996). The animals utilise feeding trees in urban and cleared habitats, as well as in forested areas, although intact landscapes provide greater densities of many dietary species than cleared land. Recent studies have shown that some urban areas can sustain GHFF populations through street tree plantings and backyard trees (McDonald-Madden et al. 2005).


In winter, GHFFs tend to congregate in coastal lowlands in the northern part of their range in south-east Queensland and northern New South Wales (Eby 2002, Roberts 2012b). In spring and summer they move south and west, and by autumn they are highly dispersed, occupying twice the number of camps as winter but in smaller populations (Eby 2003 & 2008). These general patterns are associated with latitudinal trends in the species richness and seasonality of foraging resources for GHFF in native forests (Eby & Law 2008). In particular, native forests in the northern part of the range provide relatively consistent and abundant winter resources, while nectar-producing habitat is rare at higher latitudes during winter and spring.


      1. Reproduction and Life Expectancy

Australian flying-foxes are seasonal, synchronous breeders (DECCW 2009a, Eby 2008) and polygamy is common. They are also panmitic, in that there is no geographic or group founded genetic structure.
Mating behaviour in Black and Grey-headed Flying-foxes commences in January with conception occurring in April / May (Nelson 1965, Martin et al. 1996). They have a low reproductive rate, with a single pup generally born in October / November (Martin & McIlwee 2002); although births in September can occur (P. Eby unpublished data). In 2012, very young pups were observed in the first week of September (Dowling pers. com.) in the Lower Hunter. Whilst previously reported as being capable of opportunistic breeding (Tidemann 1999), the consensus of contemporary studies describes limited plasticity in the breeding of the GHFF (O’Brien 2011).
Newborn flying-foxes are incapable of thermoregulation (Bartholomew et al. 1964). Young cling to their mothers continuously for approximately four to five weeks, after which they are left at the camp at night and suckled during the day. By the time young are three months old, they are capable of short flights and develop the skills for fully-independent foraging forays over the following weeks. GHFFs lactate for approximately six months. Weaning commences in March and continues progressively through May (Welbergen 2008).


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Grey-headed Flying-Fox and Eucalypt blossom (Eucalyptus microcorys)

Individuals reach reproductive maturity in the second year of life, but typically do not successfully raise young until the third and fourth year (Divljan 2008). However food shortages and other as yet unknown events can cause mass abortion or abandonment of young (P. Eby unpublished data), decreasing reproductive output. Studies show that death of a female often results in the death of two GHFF due to the extended period of dependency of the young (Divljan et al. 2011).


GHFFs can hybridise with P. alecto (Black Flying-fox) to produce fertile offspring (DECCW 2009a), although it is unclear whether, or to what extent, this happens in the wild.
Flying-foxes can live for over 16 years in the wild, however, average life expectancy is more likely to be under seven years (Divljan et al. 2006).


      1. Diet

GHFFs are canopy-feeding frugivores and nectivores; feeding primarily on blossom and fruit in canopy vegetation, and occasionally supplementing this with leaves (Ratcliffe 1931, Parry-Jones & Augee 1991, Eby 1995, Tidemann 1999, Hall & Richards 2000 in DECCW 2009a). The majority of animals feed on nectar and pollen from species of Eucalyptus, Corymbia, Angophora, Lophostemon, Melaleuca and Banksia. They also feed on introduced tree species in urban areas and commercial fruit crops. Over 100 native flora species are included in the diet of GHFF. Of these, 40 species of nectar plants and 43 species of fruit-bearing plants occur within the Lower North East CRA region (Eby & Law 2008). Appendix shows a diet list for the Lower Hunter.


      1. Environmental Services

Flying-foxes disperse the pollen and seeds of more than 100 species of native trees and vines. In doing so, they make a valuable contribution to the reproductive and evolutionary processes of hundreds of forest and woodland communities throughout Australia, and of many commercially valuable hardwood and rainforest trees. Various characteristics of flying-foxes contribute to their role as pollen and seed dispersers, and make their patterns of dispersal unique among Australia’s fruit and blossom feeding animals. Their mobility, territorial feeding behaviour, and colonial habit, result in wide-ranging dissemination of pollen and seeds (Eby 1996, Southerton et al. 2004, Birt 2005a). Their ability to move freely among habitat types allows them to transport genetic material, both within continuous tracts of forest and across fragmented, degraded and urban landscapes (Eby 1996, Birt 2005b), thereby protecting ecosystem functions in altered landscapes, and assisting with sustainable forest management. These services provided by flying-foxes are of inestimable ecological and commercial value.

Table 10.2GHFF in the Lower Hunter

10.2.1Foraging Behaviour

An assessment of available foraging habitat for the GHFF was undertaken by Eby and Law (2008; refer to Table 10.3). They found the following for the Lower North East (LNE) region, a broader area that includes the Lower Hunter Valley:


  • 40 species of plants occur which contribute to the GHFF nectar diet (38 Myrtaceae and two Proteaceae; refer to Appendix for full list);

  • seven of these species are highly productive:

  • Spotted Gum (Corymbia maculata);

  • Red Bloodwood (C. gummifera);

  • Pink Bloodwood (C. intermedia);

  • Swamp Mahogany (Eucalyptus robusta);

  • Grey Ironbark (E. siderophloia);

  • Forest Red Gum (E. tereticornis); and

  • Broad-leaved Paperbark (Melaleuca quinquenervia).

  • a relatively high proportion of these have regular annual flowering schedules, the highest proportion flower in December / January and the lowest in June / July. However, the frequency with which they flower varies between species, ranging from those that flower well every year (e.g. E. robusta) to those that flower well <30% of years (e.g. C. maculata);

  • 43 species of rainforest trees and lianas that occur in the LNE region occur in the GHFF fruit diet;

  • of the 961 vegetation types described in the LNE, 57% contain nectar resources for GHFF, covering 43% of the LNE and comprising 75% of the extant vegetation. However few areas contain vegetation types containing nectar resources rated as being highly productive and reliable, comprising only 2% of vegetation types which cover 0.7% of the LNE land area. Nectar resources with moderate productivity and reliability scores cover approximately 9% of the land area; and

  • only 8% of vegetation types in the LNE region, covering 3% of the land area contain species providing fruiting resources for the GHFF.

A review of foraging habitat for the Lower Hunter utilising the Greater Hunter Vegetation Map (GHMv4; Siversten et al. 2011) has been undertaken. This is discussed further in Section 14. It forms the basis for identifying foraging habitat critical to the survival of the GHFF in the Lower Hunter and setting conservation priorities for foraging habitat.
10.2.2GHFF Observations

Within the OEH Wildlife Atlas, 361 records of the GHFF are located within the Lower Hunter (refer to Table 10.4 and Table 10.6). The vast majority of these records are observations and audible detections of, presumably, commuting and / or foraging animals. A very small proportion relates to roost-site observations.


The season or bi-month in which records were detected correlates with the foraging habitat modelling undertaken by Eby & Law (2008). There is a spike in the number of detections in summer and early autumn, with low numbers detected at other times, particularly June / July and August / September.
Table 10.3Foraging Habitat - Lower North East NSW

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Table 10.4Seasonality of Records of GHFF

Bi-month

Number of Records

December / January

84

February / March

108

April / May

72

June / July

22

August / September

23

October / November

52

Grand Total

361

Source: OEH Wildlife Atlas

Table 10.5Research / Monitoring Programs

      1. Previous Studies

Few previous studies of the GHFF have included the Lower Hunter within their study area. The most commonly encountered comments regarding the use of the Lower Hunter by GHFFs are studies involving radio telemetry (radio-t) and satellite telemetry (satellite-t) methodology. As GHFF are highly mobile, at times animals are tracked into the Lower Hunter Valley. Otherwise, the Lower Hunter is included in broad studies on this species. One such example is the earliest known documented study of GHFFs undertaken by Ratcliff and published in 1931. Ratcliff observed patterns in the seasonality of camp occupation in areas between the Hunter River and Mary River in Queensland. He concluded that long distances are travelled by this species, and hypothesised about a northward trend in movement over winter (Ratcliff 1931).
Subsequent studies have demonstrated that GHFF readily shift between camps in northern NSW, the Lower Hunter and further south (Eby 1991). More recent studies utilising satellite-t to follow a GHFF tagged in Melbourne and another tagged from Currie Park (northern NSW), revealed that both animals spent time within the Lower Hunter, covering approximately 1,000 km from their initial point of capture (Tidemann & Nelson 2004).
Eby (1991) found that “P. poliocephalus in northern and central NSW appear to function as a single breeding population and should be managed as such”. A broad study has also been undertaken on GHFF foraging habitat in terms of spatial and temporal shifts in availability. Eby and Law (2008) completed an assessment of GHFF feeding habitat along the east coast of Australia, and ranked these to assist with conservation management. This strategy includes an update of this work for the Lower Hunter using the GHMv4 vegetation mapping product (refer to Section 14).
Whilst these studies demonstrate that GHFF move very long distances, and that naturally available food opportunities shift seasonally and unpredictably for this species within its range, there are also examples of permanent camps where food resources can support animals throughout the year. A study undertaken at a large camp in Sydney (Gordon) suggests that the introduction of a wide variety of Australian and exotic plants has supported permanent camp occupation (Parry-Jones & Augee 2001). Similar conclusions have been drawn for Melbourne (Williams et. al 2006). It is conceivable that Blackbutt Reserve, the only continuously-occupied camp in the Lower Hunter, is likewise supported by a broad and unnaturally diverse range of suitable foraging species for the GHFF. With the predicted growth and development described in the LHRS, similar situations may be established elsewhere in the Lower Hunter.
National GHFF surveys conducted between 1998 and 2005 showed that a small number of camps in the Lower Hunter were occupied in April / May, while only Blackbutt Reserve in Newcastle was occupied in July (Eby et al 1999, Eby 2002, 2003, 2004, Birt 2005a). Work qualifying the frugivorous diet of GHFF provides insight into how vegetation in the Lower Hunter provides foraging resources for this species (Eby 1998), whilst others have provided insight into the flowering phenology of Myrtaceous trees in relation to climatic, environmental and disturbance variables (Law et al. 2000).
Most recently, work published by Roberts et. al. (2012b) showed through improved satellite-t technology (improving detection during migration) that GHFF captured at Fraser Island and other locations in south-eastern Queensland frequented camps as far as 1,075 km to the south in Western Sydney.


      1. Current Research / Monitoring Programs

Some current research / monitoring programs are likely to offer insight into GHFF movements in the Lower Hunter. A current monitoring study associated with the Royal Botanical Gardens in Sydney involving satellite-t may assist with locating unknown camp sites in the Lower Hunter. The study was conducted at a time when a preferred dietary species, Spotted Gum (Corymbia maculata) flowered profusely in the area and camps associated with this resource contained large populations. Therefore, the study is also likely to generate data on the feeding sites used by study animals using this resource. Preliminary information from this study regarding feeding locations was used to verify vegetation-type mapping (refer to Section Table 15.9).
The National Flying-Fox Monitoring Program is a collaborative work involving DSEWPaC, CSIRO and environmental government agencies from SA, VIC, NSW, ACT and QLD. The program is funded from many sources, including the Intergovernmental Hendra Virus Taskforce and the National Environmental Research Program, which is administered by DSEWPaC. The program focuses on the population numbers and movement of the two EPBC-Act-listed species: the GHFF and the Spectacled Flying-fox (Pteropus conspicillatus). This program is being coordinated by CSIRO and involves a period of national census counts supplemented by remote sensing. The first counts were held between 14 and 16 of February 2013 and are to be held quarterly for the next four years. More details on the method for census collection and data analysis has been prepared by CSIRO (A monitoring method for the grey-headed flying-fox, Pteropus poliocephalus; Westcott et al 2011). This work will provide information on periodic use of camps in the Lower Hunter over coming years and trends in any change in population number.


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