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National recovery plan for the yellow-bellied glider (Wet Tropics) Petaurus australis unnamed subspecies Title


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1. Queensland Vegetation Management Act 1999

2. Regional Ecosystems Description Database version 5.0, Environmental Protection Agency 2007 (Biodiversity status)


Social and economic impacts

This recovery plan does not include any actions that are likely to cause any significant adverse social or economic impacts. The plan does not impose any habitat protection measures for wet eucalypt open forest on private land. The Vegetation Management Act 1999 (VMA), in conjunction with the Sustainable Planning Act 2009 (SPA) and local government planning schemes, largely determine what clearing is permissible on private property. While conservation of habitat on private land will be encouraged, such actions by landholders are voluntary. Landholders are encouraged to consider the monetary (possible tax concessions versus potential loss of future options) and non-monetary benefits of entering into ‘voluntary conservation agreements’. Planning and implementing fire management strategies on conservation land adjacent to neighbouring tenures will need to be conducted in a consultative manner with consideration for private assets.


Successful recovery efforts will have positive social, economic and educational impacts. The yellow-bellied glider (Wet Tropics) is considered a flagship animal for Wet Tropics wet eucalypt open forest. Communities are likely to benefit via continued tourism associated with spotlighting tours and other activities that appreciate the unique forest types occupied by the glider.

2. Biological information

Species description

The yellow-bellied glider (Wet Tropics) is a nocturnal and arboreal gliding marsupial. Glides over 100 m have been recorded by adults departing from tall trees and travelling downslope. Adults typically weigh 500 g (Russell 1984). The head-body length is around 300 mm, and the tail is around 450 mm long (Russell 2002). Compared with the more widespread southeast Australian populations, the Wet Tropics population is smaller and lighter in weight (Russell 1984) and may be darker in colour on the back. Goldingay et al. (2001) suggest that the reported whitish rather than yellowish belly is a function of age, with belly colour tending to yellow with increasing age. Yellow-bellied gliders produce distinctive and loud shrieking and gurgling calls (Russell 1984, Lindenmayer 2002).


There has been confusion surrounding the taxonomy and use of scientific names associated with yellow-bellied gliders. The Wet Tropics population is disjunct from the main southeast Australian populations (there is a gap of around 400 km between the Mackay area populations and the Wet Tropics population), and is usually treated as distinct based on its distribution, morphology and ecology. The EPBC Act refers to ‘Yellow-bellied glider (Wet Tropics), Petaurus australis unnamed subspecies’. The Queensland Nature Conservation Act 1992 refers to ‘Yellow-bellied glider (northern subspecies), Petaurus australis unnamed subsp.’. The Action Plan for Australian Marsupials and Monotremes (Maxwell et al. 1996) refers to Petaurus australis unnamed subsp. and uses two common names, fluffy glider and yellow-bellied glider (northern subspecies). It is clear that all are referring to the same population.
The name Petaurus australis reginae is now generally regarded as inappropriate for the geographically isolated Wet Tropics population. Designation of the subspecies was based on differences in fur colour. Further studies indicated that the colour of the belly fur varies according to the age of the individual and cast doubt on this distinction (Goldingay & Kavanagh 1990; Goldingay et al. 2001). Furthermore, the type specimen for the subspecies reginae was from a southern population (near Bundaberg) and not from the north Queensland (Wet Tropics) population. Genetic analysis and ecological differences indicate that the Wet Tropics population is an evolutionary significant unit (ESU), distinct from southern Australian populations (Brown et al. 2006). The results of this study are consistent with the recognition of the northern Queensland population as a distinct subspecies. Little information has been published comparing yellow-bellied glider populations throughout the entire range.
The naming protocol implemented by the EPBC Act (yellow-bellied glider (Wet Tropics), Petaurus australis unnamed subsp.) appears an appropriate working solution until taxonomic issues are clarified. While the succinct common name of ‘fluffy glider’ for Wet Tropics population of yellow-bellied gliders has often been used, it has not been adopted as the ‘official’ common name, and unless the Wet Tropics population is formally described as distinct, will probably remain a local name.
Life history and ecology

The yellow-bellied glider (Wet Tropics) is largely restricted to the narrow band of wet eucalypt open forest (also called wet sclerophyll forest) that provides its two key habitat resources, den trees and sap trees. Den trees, used for daytime shelter and by young animals, are primarily hollow-bearing rose gum Eucalyptus grandis (also referred to as flooded gum). A major food source is sap, almost exclusively from red mahogany E. resinifera (also referred to locally as red stringybark) (Quin et al. 1996). In contrast, southern populations of yellow-bellied gliders consume the sap of numerous tree species (e.g. Eyre & Goldingay 2005). A small number of select red mahogany trees within the home range are used for sap feeding, by chewing and chiselling through bark to access sap flow. This leads to distinctive scarring on the trunk of the trees. Other food sources include other exudates (especially nectar but also honeydew and manna), pollen and invertebrates. In north Queensland, yellow-bellied gliders are known to feed extensively on nectar and pollen of Banksia integrifolia during autumn and winter (Quin et al. 1996).


The wet eucalypt forest habitat occurs between rainforest and dry sclerophyll forest (open forest and woodland), at 600-1300 m a.s.l. (Winter 1997a). The habitat is often very narrow (usually less than 4 km wide and sometimes no more than two trees wide) and subject to fragmentation and deterioration from natural and human land management processes. Creation of gaps and clearings such as roads and easement corridors can isolate populations, fragment habitat and increase the risk of predation. For the Southern yellow-bellied glider, gaps in excess of 50 metres can act as dispersal barriers. Den trees are usually exceptionally large live rose gum Eucalyptus grandis. The preference for rose gum may relate to the presence of larger hollows that can accommodate entire social groups (R. Goldingay, pers. comm. 2007). It may also be related to reduced competition from possums for dens or reduced predation from goannas and pythons due to the smooth bark of the rose gums that makes them difficult to climb (R. Russell, pers. comm. 2007). More than one den may be used by a group. Sap feed trees are almost exclusively red mahogany (R. Russell, pers. comm. 2007). Goldingay & Quin (2004) found that gliders studied at Nitchaga, south of Ravenshoe usually used two feed trees in a territory at any given time and around five feed trees may be used over a year. Other scarred trees may occur nearby but remain unused.
Births occur throughout the year. The single young spends around 100 days in the pouch, and a further 50 days in the den before making forays outside the den, initially by clambering and jumping between branches rather than gliding. The glider lives in family groups of 2-6 individuals, which typically occupy exclusive home ranges averaging around 50 ha, but much smaller territory sizes were recorded by Russell (1984). Individuals may travel up to 1 km between den and feed trees. Group and home range size are probably related to habitat quality. Goldingay et al. (2001) studied gliders at Nitchaga, south of Ravenshoe and found that they had a highly variable social system. Lifespan is known to be at least six years (Russell 1984). Goldingay et al. (2001) also found that although gliders at Nitchaga where born throughout the year, the majority were born between June and late August.
Distribution

The current distribution of yellow-bellied gliders (Wet Tropics) remains relatively similar to that assumed to have occurred prior to European settlement, with the exception of areas where habitat clearing has occurred. The range is between Yamanie Creek catchment, just north of the Herbert River Gorge (70 km west of Cardwell) and Mt Windsor Tableland (100 km north-west of Cairns) (Winter 1997a), a distance of around 260 km (Figure 1 and Figure 2).


Three major subpopulations are identified (Maxwell et al. 1996):

  1. The Cardwell Range - Herberton Range subpopulation occurs patchily from near Atherton south to the Herbert River. This subpopulation has a narrow linear distribution 120 km long, rarely wider than 2 km and is expected to be naturally fragmented due to habitat discontinuities, particularly in the south. In addition, habitat clearance has increased the fragmentation of this subpopulation through the creation of two major gaps around Ravenshoe, the ‘Evelyn Gap’ and the ‘Butchers Creek Gap’. These gaps isolate gliders in the Tumoulin area from those in the Herberton Range to the north and those in the Cardwell Range to the south of Ravenshoe.

  2. The Mt Carbine Tableland subpopulation occurs patchily from the north branch of the Mary River (north of Mt Molloy) north to Smith Creek, a distance of 25 km. There is approximately 10 km of dry sclerophyll forest separating this subpopulation from suitable habitat on the Mt Windsor Tableland, which is believed to be a significant barrier. Gliders in the ‘Little Daintree’ area (see Hedges 2006) are the subject of biannual surveys.

  3. The Mt Windsor Tableland subpopulation is only known to occur around the north-west, west and south-west foothills of the Mt Windsor Tableland, over a distance of 20 km.

The apparent absence of the yellow-bellied glider (Wet Tropics) from suitable habitat in the Lamb Range to the north-east of Atherton and south of the Herbert River on the Seaview Range and Paluma Range is attributed to past climatic regimes (Winter 1997b).


Whether there have been any changes in abundance is uncertain, though glider numbers at Little Daintree are believed to have been fairly constant over the decade they have been monitored (Hedges 2006).



Figure 1: Potential yellow-bellied glider (Wet Tropics) habitat distribution (source: DERM 2007)


Figure 2: Yellow-bellied glider (Wet Tropics) known distribution (source: DERM 2011)

Habitat critical to the survival of the species

The yellow-bellied glider (Wet Tropics) has been recorded in 11 vegetation types (Table 3). These vegetation types comprise all of or parts of five regional ecosystems that are mapped by DERM (EPA 2007). These vegetation types are the basis for the preliminary mapping of yellow-bellied glider (Wet Tropics) undertaken by DERM (Figure 1).


Table 3: Vegetation communities in which yellow-bellied gliders (Wet Tropics) have been recorded.


Regional ecosystem

Status

Vegetation community

VMA1

REDD2

7.12.21

Least

concern


Endangered

7.12.21a:

Eucalyptus grandis tall open-forest and woodland. Granites and rhyolites.

7.12.21b:

Eucalyptus grandis tall open-forest and woodland with a well developed vine forest understorey. Granites and rhyolites.

7.12.22

Least concern

Endangered

7.12.22a:

Eucalyptus resinifera, Eucalyptus acmenoides, Corymbia intermedia, Eucalyptus cloeziana, Syncarpia glomulifera tall open-forest to tall woodland with Allocasuarina torulosa and Callitris macleayana. Uplands and highlands of the moist rainfall zone.

7.12.22b:

Eucalyptus resinifera, Eucalyptus acmenoides, Corymbia intermedia, Eucalyptus cloeziana, Syncarpia glomulifera tall open-forest to tall woodland with Allocasuarina torulosa and Callitris macleayana, and with a very well developed vine forest understorey. Uplands and highlands of the moist rainfall zone.

7.12.22d:

Syncarpia glomulifera, Eucalyptus resinifera, and Corymbia intermedia open-forest to tall open-forest, often with Callitris macleayana, and Allocasuarina torulosa. Uplands of the wet rainfall zone.

7.12.22e:

Syncarpia glomulifera, Eucalyptus resinifera, and Corymbia intermedia open-forest to tall open-forest, often with Callitris macleayana, and Allocasuarina torulosa, and with a very well developed vine forest understorey. Uplands of the wet rainfall zone.

7.12.27

Least

concern


Not

of concern



7.12.27b:

Eucalyptus tindaliae and Syncarpia glomulifera medium to tall open-forest and woodland. Uplands and highlands on shallow granitic and rhyolitic soils, of the moist rainfall zone.

7.8.15

Of

concern


Endangered

7.8.15a:

Eucalyptus grandis open-forest to woodland. Basalt.

7.8.15b:

Eucalyptus grandis open-forest to woodland, with a well developed vine forest understorey. Basalt.

7.8.16

Of

concern


Endangered

7.8.16a:

Eucalyptus resinifera, Corymbia intermedia, E. cloeziana, Syncarpia glomulifera open forest and woodland with Allocasuarina torulosa. Uplands and highlands on basalt, of the moist rainfall zone.

7.8.16b:

Eucalyptus resinifera, Corymbia intermedia, E. cloeziana, Syncarpia glomulifera open forest and woodland with Allocasuarina torulosa and a very well developed vine forest understorey. Uplands and highlands on basalt, of the moist rainfall zone.

1. Queensland Vegetation Management Act 1999

2. Regional Ecosystems Description Database version 5.0, Environmental Protection Agency 2005 (Biodiversity status)


Regional ecosystems are mapped by the Queensland Herbarium (Queensland Herbarium and Wet Tropics Management Authority 2005), and are periodically updated (e.g. following work by Stanton & Stanton 2005 in the Wet Tropics). Other projects have mapped eucalypt forest in the Wet Tropics (e.g. Harrington et al. 2005, Williams 2006) and will assist in further defining and mapping yellow-bellied glider (Wet Tropics) habitat.

The two key regional ecosystems (7.12.21 and 7.12.22) comprise 82% of the mapped extent of potential habitat. They are essential habitat when found in connection with each other. The principal habitat requirement in RE 7.12.21 relates to Eucalyptus grandis, particularly for den access (although E. grandis is also important for pollen, insects and honeydew), while the principal use of RE 7.12.22 is associated with sap feed trees Eucalyptus resinifera. Regional ecosystems fringing RE 7.12.21 and 7.12.22 also provide habitat resources and will be periodically visited by the glider. The main use of RE 7.12.27, another important ecosystem type, is likely to relate to feeding on the blossom of turpentine, Syncarpia glomulifera.

Under the Vegetation Management Act 1999 RE 7.12.21 and 7.12.22 have a Vegetation Management Class ‘Least Concern’, as the current extent of both is close to the pre-clearing extent (>90% of pre-clearing remains). However, both regional ecosystems have a Biodiversity Status of ‘Endangered’ (EPA 2007), as ‘Less than 10% remains unaffected by severe degradation (rainforest invasion, timber harvesting and weed invasion)’.
The current mapped area of potential habitat is estimated as 49,440 ha: 2470 ha associated with the Mt Windsor Tableland subpopulation, 7370 ha associated with the Mt Carbine Tableland subpopulation and 39,600 ha associated with the Cardwell Range - Herberton Range subpopulation (Winter 1997a).
Important populations

The yellow-bellied glider (Wet Tropics) is considered to be one population that has been separated from the southern populations of the yellow-bellied glider. Within this population three major subpopulations are identified.


While three subpopulations are identified, little is known about the yellow-bellied glider (Wet Tropics) population structure. No comprehensive data exist to determine:

  1. the extent to which these subpopulations might comprise smaller disjunct units

  2. the extent to which fragmentation has isolated subpopulations

  3. the barriers to dispersal and gene flow

Winter (1997a) gives a maximum population estimate of 5530 which includes the following:



  • Mt Windsor subpopulation – maximum number of individuals is 350

  • Mt Carbine Tableland subpopulation – maximum number of individuals is 1040

  • Cardwell Range - Herberton Range subpopulation – maximum number of individuals is 4140

Studies on the southern yellow-bellied glider suggest that 150 family units is the minimum to ensure a population remains viable (Goldingay and Possingham 1995).



3. Threats

Biology and ecology relevant to threats

The yellow-bellied glider (Wet Tropics) is restricted to a narrow band of wet eucalypt open forest that is an ecotone between rainforest and drier woodland ecosystems. Specific habitat requirements critical to survival are den trees (typically veteran rose gums Eucalyptus grandis), and sap feed trees (red mahogany E. resinifera), and the connectivity of the two.


Identification of threats

Several threats are affecting the survival of the yellow-bellied glider (Wet Tropics). The threats principally relate to habitat alteration. In order of likely significance these are:



  • changed vegetation structure due to change in fire regime and other factors (major)

  • clearing and fragmentation of habitat (moderate)

  • grazing regime (minor)

  • barbed wire fencing (minor)

  • climate change (unknown)

The identified threats may have one or several of the following consequences:



  • habitat loss

  • habitat alteration and fragmentation

  • limited eucalypt recruitment

  • habitat migration

  • loss of individuals


Changed vegetation structure due to change in fire regime and other factors (major)
Winter (2004) considered the loss of habitat through rainforest encroachment to be the principal threat to the glider, particularly where rainforest encroachment has reached an irreversible state where it has progressed to a highly modified structure of a denser closed forest with eucalyptus emergents (DERM QPWS 2011).
Likely impacts on the glider from altered vegetation structure due to changed fire regimes and other factors include:

  • habitat loss (including dens)

  • habitat alteration and fragmentation (especially rainforest encroachment) affecting movement

  • canopy disruption affecting movement

  • limited eucalypt recruitment affecting food source and potential dens

The transition from a tall open forest to a thicker, denser structure of a closed forest through rainforest encroachment is thought to impede the passage of the yellow-bellied glider (Wet Tropics), largely negating the competitive advantage of gliding (M. Parsons, pers. comm. 2011). Changes in vegetation structure may also impact on food and den availability.


A number of factors are thought to have contributed to rainforest expansion. Forestry and grazing activity has changed forest structure and thereby fire dynamics, and altered climatic factors (elevated moisture regimes). However, these suggestions have not been well explored. Harrington & Sanderson (1994) showed that 50-70% of tall open forest was ‘captured’ by rainforest expansion between the 1940s and 1990s. Harrington et al. (2005) has updated these estimates stating 80% of rose gum Eucalyptus grandis dominated forest has been encroached upon. However, given the significant impacts of changes in management practices on these forests by 1940, including a general cessation of traditional burning regimes and significant use for logging and grazing, the condition of forests in the 1940s may not be representative of pre-European forest structure. Bradford & Harrington (1999) studied habitat in the early stages of rainforest encroachment and found such areas were used for sap-feeding, but doubted sap trees would thrive or reproduce if rainforest continues to develop.
Traditional burning is likely to have been reduced and eventually discontinued during the late 1800s and early to mid 1900s. At the same time fires associated with grazing and forestry activity were introduced and came to dominate forest management for most of the 1900s. However, in the last few decades the expansion of human infrastructure within and adjacent to some habitat, and reduced grazing activity, has meant fire suppression has been used in managing this habitat.

A lack of burning in Wet Tropics wet eucalypt open forest is generally regarded as causing widespread habitat alteration, especially the conversion of grassy understoreys to rainforest. Research does not show that fire of any intensity or frequency will necessarily stop rainforest encroachment (e.g. Williams 2000). Typically rainforests will not burn due to moisture, microclimate conditions and a lack of flammable grasses (Bowman 2000). Scorching of rainforest edges may occur with the presence of high biomass grasses or lantana (Low 2010), particularly within the drier southern half of the wet tropics bioregion. Heavily disturbed rainforest is potentially flammable in severe fire weather. The potential for cyclones and severe fire weather events are expected to increase under climate change predictions (Low 2010).


Fires can play an important role in maintaining moist, open woodland for the yellow-bellied glider (Wet Tropics). Longer inter-fire intervals may lead to a transition from an open to a closed structure (DERM QPWS 2011). Planned burning helps to maintain representative examples of this tall open forest vegetation group, especially grassy dominated ground layers, which have a propensity to transition from open grassy eucalypt forest to closed forest with a lack of fire (DERM QPWS 2011).
The loss of den trees has been attributed to high-intensity burning (Eyre 2005, Gibbons et al. 2000) with fire scars developing at the base of rose gums and contributing to tree collapse. However, the significance of den tree loss associated with fire is unknown. Additionally Adkins (2006) has shown that fire can also play a positive role in hollow development.
Fire management in tall open forest requires a carefully considered integrated approach. Early in the year, the surrounding fire-adapted communities should be burnt to create areas of low fuel that help contain higher severity late season fires. Late season conditions are often required to allow tall open forests to dry sufficiently so they can carry fire. The Department of Environment and Resource Management, Queensland Parks and Wildlife Service has developed planned burn guidelines for the Wet Tropics Bioregion of Queensland (DERM QPWS 2011). These guidelines provide direction towards implementing appropriate fire management practises within a changing climate, including for yellow-bellied glider habitat. The guidelines include information on fire parameters for managing tall open forest at an advanced stage of transitioning.
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