«PLATYPUS Contents 1.0 Introduction 2 2.0 Conservation Status 3 3.0 Distribution 3 4.0 Ecology 4 5.0 Threats 7 6.0 Conservation 8 7.0 Research 8 8.0 ...»
1.0 Introduction 2
2.0 Conservation Status 3
3.0 Distribution 3
4.0 Ecology 4
5.0 Threats 7
6.0 Conservation 8
7.0 Research 8
8.0 Management Intent 9
9.0 Further Information 13 Tables Table 1: Ofﬁcial Conservation Status of Brisbane City’s Platypus 3 Table 2: Breeding Seasons 6 Table 3: Management Actions 10 Table 4: Habitat Management Guidelines 11 Maps Map 1: Records of Platypus in Brisbane 5 PLATYPUS
1.0 Introduction Brisbane is recognised as one of the most biologically diverse capital cities in Australia, supporting some 1500 plant species, 523 vertebrate animal species and innumerable invertebrate species.
Brisbane is also part of one of the fastest growing urban regions in Australia. This growth is placing signiﬁcant pressure on the ecosystems and wildlife of the city. Population pressures and urban development, resulting in the loss and fragmentation of habitat, continue to be the greatest threats to the protection of biodiversity (Brisbane SOE 2001). Since 1990 the rate of clearing has decreased markedly.
However, even with no further loss of habitat, some existing ﬂora populations within the city are at risk of local extinction because the small, isolated, remaining habitat areas cannot support them. Other signiﬁcant threats include pest animals and plants and inappropriate ﬁre regimes. The challenge is to maintain and restore the city’s biodiversity while accommodating urban growth.
Brisbane City Council has responded to this challenge with the Brisbane City Biodiversity Strategy, an important part of Council’s Living in Brisbane 2010 vision for a clean and green city. The strategy outlines a range of initiatives designed to secure the long-term conservation of the city’s outstanding biodiversity values using available public, community and industry resources. Conservation Action Statements are among these initiatives.
Conservation Action Statements clearly state Council’s management intent for the city’s most threatened species, and outline key strategies and actions for their management in Brisbane.
This Conservation Action Statement addresses the platypus (Ornithorhynchus anatinus), which is identiﬁed as a signiﬁcant species within Brisbane as per Council’s Natural Assets Planning Scheme Policy (Brisbane City Council 2000, Brisbane City Plan, vol 2, schedule 4).
This Conservation Action Statement will be updated every two to ﬁve years to reﬂect new information and progress on conservation actions. For more information about this or any other Conservation Action Statement, visit Council’s website at www.brisbane.qld.gov.au or phone Council on 3403 8888.
1.0 Introduction continued...
Aims This Conservation Action Statement details Council’s management intent for long-term protection and
conservation of the platypus within Brisbane by:
• collating existing information on the distribution, ecology and management requirements of this species within Brisbane and surrounds
• identifying key threats that signiﬁcantly impact upon this species within Brisbane
• identifying gaps in existing knowledge of the habitat and management requirements of this species and research priorities
• detailing practical and affordable strategies and actions that support the long-term protection and conservation of this species within Brisbane.
2.0 Conservation Status The conservation status of a species will inﬂuence how it is managed. ‘Threatened’ species are typically accorded a more stringent management regime than ‘common’ species. Various conservation registers identify the status of fauna species at local, state and national levels. The current status of the platypus is provided in Table 1.
Table 1: Ofﬁcial Conservation Status of Brisbane City’s Platypus
1 Brisbane City Council 2000, Brisbane City Plan 2000, Natural Assets Planning Scheme Policy, vol. 2 2 Queensland Nature Conservation (Wildlife) Regulations 1994 under the Nature Conservation Act 1992 3 Environment Protection Biodiversity Conservation Act 1999
3.0 Distribution 1 National/State
• East coast of Australia from Cooktown in Queensland through to the Victorian-South Australian border.
• Also sighted throughout Tasmania (Stone 1983; Carrick 1995).
• Sparse in South Australia (Serena 1995; Grant 1991).
• In September 2001, PlatySearch recorded over 400 sightings from more than 100 Queensland waterbodies (QPWS 2001).
1 Unless otherwise stated, the information in this section is from Muscat (2003).
3.0 Distribution 1 continued...
Local The platypus is usually spotted in the west of the city; records for the eastern and southern waterways are few and largely unconﬁrmed. However, there are records of the platypus in the waterways throughout all districts of Brisbane. The 2001 PlatySearch survey also recorded 26 sightings of the platypus in the greater Brisbane area, including the Caboolture and North Coast regions (QPWS 2001).
The platypus has been recorded from a number of locations across Brisbane:
• Brisbane River (particularly within the upper reaches), Enoggera Creek and Enoggera Reservoir, Ithaca Creek, Fish Creek, Cubberla Creek, Farm Creek, Pullen Pullen Creek, Moggill Creek, Gold Creek and Gold Creek Reservoir and Kholo Creek.
• Cabbage Tree Creek, Albany Creek, South Pine River, Nundah Creek, Downfall Creek and Upper Kedron Brook.
• Norman Creek, Scrubby Creek (within Karawatha Forest), Oxley Creek and tributaries, Mt Ommaney Creek and Jindalee Creek.
• Tingalpa Creek; signiﬁcantly restricted and limited in numbers in the eastern suburbs due to the general degradation of waterways within this area.
Veriﬁed platypus records for Brisbane are shown on Map 1.
4.0 Ecology 2 Habitat
• Occupies a variety of permanent waters but may also use temporary or man-made water bodies particularly when these are linked to permanent natural streams or rivers (Williams and Serena 1999;
• Occurs in fast, slow-ﬂowing and still waters (Low 1993).
• Predominantly freshwater species and rarely seen in brackish and salt water (Qld DEH 1992).
• Prefers ﬂowing river or stream waters; habitat may include a series of pools typically over ﬁve metres in depth (with little accumulated sand in the pools), connected by cobbled rifﬂe areas of shallow water.
• Prefers waterways with relatively steep earth banks (greater than 1m in height) in which to build burrows (Williams and Serena 1999). Male and female platypuses build and sometimes share ‘resting’ burrows. Burrows extend at a shallow depth (50 centimetres below ground) for up to 30 metres (Grant, 1995). Several burrows may be used over a designated home range.
• Requires long sections of healthy riverine habitat for its long-term survival; isolated patches of suitable waterway are unlikely to sustain a population in the long term (Williams and Serena 1999).
• Preferred banks may include overhanging riparian vegetation which provides some shelter and food for benthic (bottom-dwelling) organisms on which the platypus feeds.
4.0 Ecology 2 continued...
• An opportunistic, carnivorous predator.
• Feeds predominantly on benthic organisms (eg. crayﬁsh, shrimp, worms, freshwater molluscs) and the larval and adult forms of many insects (eg. caddisﬂies, stoneﬂies, mayﬂies, dragonﬂies, damselﬂies, beetles and bugs). Benthic organisms are usually associated with large woody debris, undercut banks and a coarse particulate substrate (eg. cobble, gravel, pebbles) (Serena et al. 2001a).
• Feeds incidentally on nektonic (free-swimming) animals (eg. small ﬁsh, insects, frog and ﬁsh eggs).
• Typically feeds for 8-14 hours in any 24-hour period; usually forages through the night but may feed during daylight, particularly on overcast days.
• Consumes about 15-30% of its body mass in food per day (Serena et al. 2001a).
• Forages by searching along and digging into undercut banks. It also forages along shallow rifﬂe waters and dives into the deeper waters of pools (Serena et al. 2001b). When diving, the platypus stores small food items temporarily in special cheek pouches. The platypus grinds up the food in these pouches when surfacing between dives.
• Mates between July and October (earlier in the northern areas of their range) (Table 2).
• Females move to self-excavated nesting burrows to incubate their eggs and subsequently stay in, or close to, these burrows to suckle young for a three to four month period before emerging with the young early in the new year. Nesting burrows may extend as far as 30 metres from the water’s edge.
• Females may choose not to breed annually; this is assumed to be a response to unsuitable environmental conditions.
• Difﬁcult to deﬁne interbreeding populations as habitat is largely continuous.
Table 2: Breeding Seasons (green shading indicates breeding months)
Platypus* * Breeding season occurs earlier in the northern areas of their range Movement Patterns
• Essentially sedentary and solitary.
• Home ranges of male may extend over seven kilometres; males known to travel more than 15 kilometres during and prior to the breeding season.
• Females may forage up to 10 kilometres (Williams and Serena 1999).
• Typically travels over at least one quarter of home range length during one foraging period, typically 8-14 hours per day (Gardner and Serena 1995).
• Juvenile males disperse but the territories of males may overlap.
• Males believed to move into more deﬁned and separated core areas during the breeding season.
2 Unless otherwise stated, the information in this section is from Muscat (2003).
5.0 Threats 3 Waterway Modiﬁcations
• Engineering works (eg. construction of dams, bank grading, channelisation, piping, weirs and culverts) can limit available habitat.
• Concentrated discharge of stormwater to creeks causes scouring, siltation and turbidity, which destabilise burrows and degrade instream habitat (Carrick and Grimley 1994).
• Localised pumping reduces water levels below that which can sustain benthic fauna on which the platypus feeds.
• Deposition of gravel reduces water levels below that which can sustain benthic fauna.
• Vegetation loss destabilises platypus burrows and reduces instream shelter, habitat and food for benthic fauna.
• Vegetation loss permits direct ﬂow of stormwater and associated pollutants into the waterway, reducing the habitat for benthic fauna.
Poor Water Quality
• Use of pesticides and chemicals reduces water quality and the amount and type of food available for the platypus (Grant and Carrick 1978).
• Potential predators include eels, water rats and crocodiles (Grant 1995), as well as raptors, owls, foxes, dogs and cats.
• Carpet pythons, goannas and water rats may attack the eggs and young of the platypus while in burrows (Williams and Serena 1999).
• Tracks too close to watercourses contribute to bank erosion and may encourage predation by domestic pets (eg. dogs and cats).
• Broken glass, metal, wire, ﬁshing line, ﬁshing hooks, elastic bands, plastic jar seals and rings may wrap around the limbs, necks and chests of the platypus impeding its movement and ability to feed.
• The platypus drowns easily in ﬁshing nets, submerged drum or eel nets and unattended nightlines (Williams and Serena 1999).
6.0 Conservation Several Brisbane City Council biodiversity initiatives are contributing to the protection and management
of the platypus and its habitat across the city. Key initiatives include:
• Bushland Acquisition Program: Through this program more than 1900 hectares of the city’s most signiﬁcant lowland habitats have been purchased and protected to date.
• Conservation Partnerships: More than 240 private properties have established conservation partnerships with Council, covering some 750 hectares of principally lowland habitats in signiﬁcant platypus areas.
• Conservation Reserve Estate: More than 12,500 hectares of parkland including 7000 hectares of bushland and wetland reserves are managed and protected. This reserve network provides habitat for Brisbane’s signiﬁcant species.
• Natural Assets Local Law: Under the Natural Assets Local Law 42% of the city area is now better protected from pre-emptive clearing.
• Brisbane City Council City Plan: The City Plan designates a green space system throughout the city to recognise and protect the contribution of open space areas to ecological functions. The City Plan’s Waterway Code, Biodiversity Code and supporting Ecological Assessment Guidelines provide performance criteria and acceptable solutions to protect signiﬁcant biodiversity values on, or adjacent to, proposed development. The City Plan also includes statutory schedules of ﬂora and fauna species considered signiﬁcant in Brisbane, recognising species signiﬁcant at a city-wide or regional level.
7.0 Research The Great Queensland PlatySearch, planned and coordinated by the Queensland Environmental Protection Agency, was undertaken to gather high quality data on the platypus’ distribution (QPWS 2001).
This was a very successful project, with 405 sightings throughout Queensland; 173 of these were from the
greater Brisbane area. Recommendations arising out of the PlatySearch survey are to: