Petalura gigantea (Family Petaluridae), commonly known as the Giant Dragonfly or Southeastern Petaltail is a very large dragonfly which may have a wingspan up to 12.5 cm. It is recorded from peat swamps, bogs and seepages along the coast and ranges of NSW from near the Victorian border to around the Qld border. It is listed as Endangered in NSW under the NSW Biodiversity Conservation Act2016, with habitat loss and degradation identified as the main threats. In addition to the large size and widely separated dark eyes, the species (and genus) is characterised by a long pterostigma (darkened cell) towards the end of the leading edge of the wings, and large, petal-shaped, anal appendages in adult males (Figure 1). Adult females lack the conspicuous anal appendages and are somewhat bulkier than males (Figure 2). These features distinguish it from other very large dragonflies such as Austrophlebiacostalis. Various Bushcare and Swampcare sites in the Blue Mountains include peat swamp habitat of Giant Dragonflies.
The Petaluridae (“petaltails”) can be traced back to the late Jurassic and currently includes 11 known species around the world, including the endemic Australian genus Petalura with five species. The family is unique amongst dragonflies, in that larvae of nine of those species (including all Petalura species) excavate (sometimes complex) burrows which extend below the water table in peaty soils and which they occupy and maintain for their entire larval stage. The deepest burrow recorded for a petalurid worldwide was a P. gigantea burrow I investigated, which was 75 cm deep. These dragonflies have very long larval stages; extrapolation from recent studies suggests a larval stage of at least six years in P. gigantea, and possibly 10 or more in some situations. Larvae reach a length of 4.5-5 cm. Larvae feed on a range of small invertebrate prey within their burrows, including worms and nematodes, and are likely to act as ambush predators of larger prey from within their burrow entrances, feeding on above ground invertebrates, such as spiders, crickets, cockroaches, and perhaps small frogs, such as Crinia signifera. Larvae with submerged burrow openings in shallow pools can also prey upon other dragonfly or damselfly larvae within those pools. It is possible (but unknown) that they also leave their burrow openings temporarily to forage under suitable conditions, such as at night and during rain. I have recorded above ground chambers above their burrow openings, within litter layers and Sphagnum hummocks, which they may use for foraging purposes. Larvae leave their burrows and climb the nearest shrub or sedgeland vegetation to undergo emergence (ecdysis) to the adult stage, usually leaving their larval skin (exuvia) attached to their shrub or sedge emergence supports. The presence of exuviae confirms a site as a successful breeding site. Emergence may commence in early October in some years in some sites and extend into January, but normally appears to commence during November, at least in the Blue Mountains.
Adults live for a maximum of one summer flying season, which extends into February at least, with occasional late flying individuals having been observed on one occasion as late as mid-March in the Blue Mountains. Adults are predatory upon other flying insects during flight and consume a range of prey, including other dragonflies and damselflies, butterflies, moths, grasshoppers, cicadas, wasps, and various types of flies, including crane flies. Adults typically return to a perch to consume prey. Adults spend much time perched in sedgeland and shrub vegetation, interspersed with generally short flights associated with foraging, mating, and in the case of males, territorial interactions. Adult females typically leave their larval swamp habitat following emergence and only return to a swamp habitat for breeding purposes. There is no courtship behaviour and mating generally occurs in swamp habitat with the pair perched in sedge or shrub vegetation. Egg-laying (ovipositing) involves insertion of the ovipositor into the wet, organic-rich soil substrate, into fissures in the substrate, or amongst or under live or decomposing plant material overlying the substrate. Females typically walk along the soil surface or perch within covering vegetation or on litter while ovipositing. They do not appear to oviposit into substrate covered by more than 1-2 mm of water. Most adults encountered in swamp breeding habitats are males, who are typically territorial in swamp habitat. Predation of adults by birds, skinks and spiders has been observed and dead individuals have been found in spider webs.
Petalura gigantea is considered to be an obligately groundwater-dependent species. Although the burrowing larval habit confers ecological benefits, including increased environmental stability, and some protection from the effects of fire, flood, drought and above ground predators, the species groundwater dependence and restriction to peat swamp habitats places it at increased risk in the event of any reduction in groundwater levels (e.g., due to groundwater abstraction, tunnel or pipeline boring, and longwall coal mining), more intense fire regimes, and the potential compounding effects of rapid climate change. Loss and degradation of habitat as a result of urban and transport infrastructure development, agriculture, forestry, and longwall coal mining continue to threaten the species through loss and degradation of habitat.
Figure 1. Male Petalura gigantea perched on razor sedge, Lepidosperma limicola, in a Blue Mountains Swamp. Note the conspicuous petal-shaped appendages at the end of the abdomen. Photo: Ian Baird
Figure 2. Female Petalura gigantea perched on Acacia ptychoclada in a Blue Mountains Swamp. Photo: Ian Baird
The Swamped by Threats Project, a partnership between BMCC, CTLLS, NPWS and Forest NSW, has reached the halfway mark. The project aims to conserve the ecological integrity and habitat quality of priority swamps for the endangered and swamp dependant Blue Mountains Water Skink and the Giant Dragonfly of the Blue Mountains and Newnes Plateau. The innovative ten year project is funded through a $750,000 Save Our Species (SOS) Partnership Environmental Trust grant.
A key focus of the project in the Blue Mountains has been the restoration of the natural hydrology of swamp systems which have been disrupted by stormwater flows from urbanised catchments, resulting in erosion, channelisation, de-watering, sedimentation, and weed invasion. Works have included stormwater outlet stabilisation, gross pollutant traps, raingardens, stormwater infiltration and integration structures and soft engineering swamp rehydration structures, as well as weed control. The sixteen priority swamp systems being targeted include Connaught, Yosemite, Marmion Road, North Street, the Gully, McCrae’s Paddock, Leura Falls, East Leura, Jamison Creek, Central Park, Wentworth Falls Lake, Franks Creek, Kittyhawke, Duperry/Clarendon Swamp, Red Gum Park, Lawson Pool and North Lawson Swamps.
A big thank you goes out to all the Bushcare and Swampcare volunteers whose ongoing on-ground efforts are making such a valuable contribution of in-kind hours in support of the grant funded work.
This project has been supported by the Hominy Bakery in Katoomba who provide the catering for these events “You know the food is good when everyone’s silent” said Katy O’Neill at the Valley View Swampcare Event.
Blue Mountains City Council Media Release 08 October 2020
Efforts to protect and conserve several rare and endangered forest areas in the Blue Mountains will be amplified, after Council was awarded a $350,000 grant by the NSW Environmental Trust.
Over the next four years the funds will be used for the Forests for the Future project, which seeks to restore and protect unique environments in a number of Council managed reserves between Glenbrook and Springwood.
Working in partnership with the NSW Save our Species program and Hawkesbury River County Council, the project will help conserve the critically endangered Sun Valley Cabbage Gum Forests and endangered Blue Mountains Shale Cap Forests across their entire range. Iconic threatened species which inhabit these forests, such as the Powerful Owl, the Tiger Quoll and the Koala, are also expected to benefit from the restoration works.
Blue Mountains Mayor Mark Greenhill said: “The Forests for the Future project is part of our ongoing commitment to best practice environmental management.
“As a City within a World Heritage Area, it’s our job to protect our local environment, especially those areas which have rare or endangered species. Some of our environment is unique to the Mountains, and that needs to be conserved,” he said.
The works – that are able to get underway – include weed control, bush regeneration, stormwater mitigation, fencing and track rationalisation at Deanei, Else Mitchell and Patterson Reserves in Springwood, Sun Valley Reserve in Sun Valley, Blaxland War Memorial Park and Wascoe Park in Glenbrook.
Works will also include vegetation mapping, as well as education for schools, land owners and the community.
This year marks the 20th Anniversary of the Greater Blue Mountains region being granted World Heritage status by the United Nations. To find out more about Council’s work to conserve our local environment, visit the Protecting and Restoring Biodiversity webpage at www.bmcc.nsw.gov.au/protecting-and-restoring-biodiversity.
AABR is progressively providing online material to assist landholders undertake ecological weed management after the extensive wildfires of spring-summer 2019-20. If you are a land manager or willing volunteer, please check out our resources below and learn what you can do to help recovering natives that are experiencing competition from regenerating weed!
First Aid for Burned Bushland (FABB) is the place the see the resources AABR is developing to provide guidance for assisting in the recovery of our bushland after the fires last spring and summer. Click the link below to see more…
BMCC, Sydney Trains and John Holland engineering contractors have worked with the community on a major restoration project. The project focussed on revegetation and restoration of Fairy Bower Reserve, Mount Victoria, and was funded by Sydney Trains as a Biodiversity Offset during the Mount Victoria Area Remodelling (MVAR) Project.
The primary goal was to increase biodiversity and habitat values at the site through planting of native species, improved access to the reserve and vehicle management, improvements to site drainage and tree and shrub weed control.
Central to this project was the involvement of the Fairy Bower Bushcare Group, who planted over 200 plants in the reserve to protect, restore and enhance the environment.
MVAR Project Manager, David Hugo said, “The Biodiversity Offset Scheme is a great initiative and in this case, the MVAR Project is proud that we are able to leave behind a small legacy for the people and visitors to Fairy Bower, Mount Victoria to enjoy after we have gone”.
Sydney Trains’ effort was appreciated by Council’s Bushcare Team Leader, Sandy Benson. “We again would like to extend our thanks for your support and willingness to collaborate with Council and our local community to provide for such a high-quality outcome,” she said.