ACT State of the Environment 2007
Indicator: Native species
The ACT is located within two bioregions (Interim Biogeographic Regionalisation for Australia – IBRA): the South East Highlands bioregion and the Australian Alps bioregion. 17 species and 2 communities are listed as endangered and 14 as vulnerable (as of March 2008) under the Nature Conservation Act 1980 (ACT). Several species, including the Spotted-tailed Quoll and two orchids, were declared threatened during the reporting period.
In the reporting period, drought and its impact on natural environments was a recurring theme adding to the pressures previously reported. Recovery of ecological communities affected by the 2003 bushfire was widely observed, although it will be some years before many tree-dominated communities reach full maturity. Birds are one faunal group that has recorded significant change, due in part to the prolonged drought.
While there is a relatively high level of habitat protection in the ACT, including lowland woodland and grassland, some native species listed as endangered (such as the Northern Corroboree Frog) show evidence of continued decline and others (such as the Grassland Earless Dragon) are threatened by relatively new pressures.
With climate change and growth in the human population of the Canberra region the demands on water resources are likely to increase and scrutiny of water resource management is also likely to grow. Current research into the ACT's threatened fish fauna is generating information on species' needs, which is being used to support sound decisions about use of water resources. The long-term conservation of aquatic and riparian ecosystems requires a continuing commitment to ecological research and adaptive management of water resources and threatened species in the region (Environment Australia 2000).
What the results tell us about the ACT
The Canberra Ornithologists Group (COG) carries out extensive monitoring and recording of birds in the ACT and region. It publishes an Annual Bird Report that summarises all its records of birds in the Canberra region each year. The report covers the area from Yass–Goulburn (north) to Bredbo (south), Wee Jasper–Adaminaby (west) to Lake Bathurst (east). The latest report is for 2005–06. As well as this general reporting, COG also conducts focused surveys, including the Garden Bird Survey (celebrating its 25th year in 2005–06) and the Woodland Bird Survey that began in 1998.
As a compilation of observations, the Annual Bird Report states that it cannot be considered comprehensive or accepted as an accurate reflection of the status of any species; however, it is an indicator of both possible trends and the influences of environmental conditions. In addition, it should be noted that the reporting period and the previous six months included several significant environmental events that have impacted birds. The devastating 2003 bushfire burned most of Namadgi National Park, particularly affecting wet forest habitats, as well as the Murrumbidgee River corridor and the Lower Cotter Catchment. Extensive rural land and pine plantations west of Canberra were also burned and this has opened up and altered that landscape significantly. Added to the fire impacts, has been the effect of the longest drought on record.
From 1995–96 to 2001–02, the number of species reported has been in the range 206 to 217 (Annual Bird Report 2001–02). In the reports for 2002–03 to 2005–06 the number ranged between 216 and 233 species. The 2005–06 total may have been boosted by a special survey effort in October 2005 in addition to the wettest spring in 5 years, a hot summer and one of the driest autumns on record.
In the Annual Bird Reports for 2003–04 to 2005–06, COG noted:
- records of a wide variety of birds associated with wetlands, including Glossy Ibis and many crakes and rails
- improving recording rates for many wet forest species (affected by the 2003 bushfire) such as the Superb Lyrebird, Wonga Pigeon and Cicadabird, Bassian Thrush, Red-browed Treecreeper, Eastern whipbird and Pilotbird
- the Yellow-tailed Black Cockatoo returning to more usual numbers having been recorded more frequently in urban areas following the 2003 bushfire
- an influx of Flame Robins (an early coloniser of fire affected areas) to lowland areas (including cleared pine forests) immediately following the bushfire; however, this influx appears to be on the wane
- superb Lyrebirds at Tidbinbilla Nature Reserve showing a very slow recovery from the bushfire
- records of raptors, such as the Swamp Harrier, Black-shouldered Kite and Black Falcon (possibly related to drought and post-fire mouse plague)
- an influx of White-winged Trillers and a larger than usual number of Swift Parrots (60–70 birds) in autumn 2005, both likely to be related to the drought
- first known record for the ACT of the White-browed Babbler and the first record since 1943 of the Blue-faced Honeyeater
- of the 177 species of bird reliably recorded as having bred in the region 120 (68%) did so in 2005–06
- the 10 most abundant garden birds were Galah, Sulphur-crested Cockatoo, Common Myna, Common Starling, Silvereye, Crimson Rosella, Pied Currawong, Australian Magpie, House Sparrow, and Red Wattlebird; seven of these are native and three exotic species (the ranking of these species has changed little since 2003)
- a decreasing trend for the threatened Hooded Robin and low numbers of the threatened Brown Treecreeper.
In 2007, unpublished COG data indicates:
- unusual records of three species of inland honeyeaters (Black, Black-chinned and White-fronted), likely to be related to the continuing drought inland
- a Powerful Owl in the Australian National Botanic Gardens over several months in autumn–winter 2007.
A species of interest (listed in the ACT as a vulnerable species) is the Superb Parrot (Polytelis swainsonii) that is recorded regularly but in modest numbers, as the ACT is on the edge of part of its natural distribution, and breeding requires mature eucalypts with hollows. The summer of 2005–06 saw an influx of unprecedented numbers to Canberra, with 30–40 birds, including many dependent young in the suburbs of Belconnen, mostly at Mount Rogers in Fraser. Superb Parrots feed on psyllids (a small insect on eucalypt leaves), and on acacia seed pods and grass seeds, illustrating the importance of native vegetation in parks and reserves. In the summer of 2006–07 a similar influx of Superb Parrots was recorded in Canberra with nesting recorded at Harrison and Goorooyarroo Nature Reserve.
COG data indicate that breeding territories of the Little Eagle (Hieraaetus morphnoides) have declined from 13 in the 1980s to only two known sites (both in the Molonglo Valley) in 2006. COG believes this decline is due to loss of local woodland habitat and competition from the larger Wedge-tailed Eagle, together with the decline of rabbits (a prey species) and paucity of alternative prey species. The breeding territories in the Molonglo Valley may be affected if the proposed urban expansion occurs in the northwestern parts of the valley.
The Glossy Black Cockatoo (Calyptorhynchus lathami) is an uncommon to rare visitor to the ACT. It is a specialist feeder on seeds of Drooping She-oak (Allocasuarina verticillata), a small tree that is patchily distributed, but large stands are found in the Mount Majura and Mount Ainslie Nature Reserves. During 2003–04 a larger than usual number of birds (about 16) was recorded from Mount Majura to Mount Ainslie, as well as a breeding record. This habitat is vulnerable to fire that can kill the trees.
A special survey of birds in grassy woodlands commenced in 1998 and in 2007 included 15 locations. Results from this survey indicate:
- several species (Diamond Firetail, Jacky Winter, Crested-Shrike Tit and Varied Sittella) appear in low numbers
- the Hooded Robin shows a clear, decreasing trend with a 24% drop in occupancy rate of territories from 2004 to 2005; this is worrying, as very small groups of these birds are found in only a few woodland survey locations around Canberra
- the Scarlet Robin also showed a declining trend between 1998 to 2004 and a sharper decline in 2005; this trend is not evident from records in habitats other than grassy woodlands
- the Superb Fairy-Wren, White-plumed Honeyeater and Grey Currawong (resident in grassy woodlands) also show significant decreasing trends
- species showing increasing trends include Crested Pigeon, Sulphur-crested Cockatoo, Galah, Weebill, Speckled Warbler, Noisy Miner, White-winged Chough, and Australian Raven.
A post-graduate research project is being planned to commence at the Australian National University into the habitat use of woodland birds with a particular emphasis on birds threatened by urban expansion. When complete it is hoped that research will provide scientific information that will help those responsible for planning and managing woodland bird habitat in the ACT and surrounding region (COG 2006).
Worldwide, the presence (or absence) of frogs is considered to be an indicator of the environmental health of wetlands and other aquatic habitats. Over the past few years a community-based frog-monitoring program has developed in the ACT under the guidance of the ACT and Region National Water Week Community Frogwatch program. Frogwatch volunteers now undertake a census in spring each year at over 140 sites, most of which are located east of the Murrumbidgee River mainly in the urban parts of the Molonglo, Ginninderra and Southern catchments. Some census sites are located east of the ACT, in the Queanbeyan and Molonglo River catchments to the east of the ACT, and are beyond the scope of this report.
Frogs are detected by their species-specific calls; recorded on site and analysed with the technical assistance of ACT Government and University of Canberra ecologists. As frog calling is usually associated with breeding activity, a nil result may not necessarily mean that any particular species was not present at the time of the census. What is more important is the trend over time in the number of species at a site and the abundance estimate.
A Frogwatch report is published annually and is available at www.ginninderralandcare.org.au. The 2006 census was conducted during the recent drought, when many wetlands and water bodies were under severe stress. Results for the ACT census sites since commencement of Frogwatch are summarised in Table 1.
The results indicate:
- The three most common species are Plains Froglet (Crinia parinsignifera), Common Eastern Froglet (Crinia signifera), and Spotted Grass Frog (Limnodynastes tasmaniensis).
- The number of sites where frogs were detected in 2006 was lower than the number in 2005 (except Whistling Tree Frog (Litoria verreauxii)) and no frogs were detected calling at one-third of the sites visited in 2006, compared to 9% in the 2005 census. This is attributed to the drought conditions that were prevailing in 2006.
- One species (Spotted Burrowing Frog (Neobatrachus sudelli)) was only detected in 2004 and 2005 and at only two and one sites respectively. The species is an opportunistic breeder, staying burrowed in the ground for most of the year and coming active during periods of wet weather when the ground is saturated.
- In 2006 over half the sites monitored had either zero or one species recorded. This is different to the wet spring in 2005 when the median number of species recorded across all ACT sites was three (McConville 2007).
|No. sites where detected||11||49||67||70||38|
Common Eastern Froglet
|No. sites where detected||15||68||78||81||34|
Eastern Banjo Froglet or Pobblebonk
|No. sites where detected||13||38||21||55||16|
|No. sites where detected||0||7||8||17||8|
Spotted Grass Frog
|No. sites where detected||7||57||75||85||39|
Peron's Tree Frog
|No. sites where detected||1||23||33||36||21|
Whistling Tree Frog
|No. sites where detected||5||9||21||7||15|
Spotted Burrowing Frog
|No. sites where detected||0||0||2||1||0|
|No. sites where detected||0||15||29||33||5|
|Total no. of sites surveyed (ACT)||20||95||117||126||111|
Key: * 1–5 frogs recorded calling; ** 5–20 frogs recorded calling
Source: McConville R 2007, ACT and Region Community Frogwatch Census Report 2006, Ginninderra Catchment Group, Canberra
Plant species list for the ACT
The ACT Government and the Australian National Herbarium (Centre for Plant Biodiversity Research) have been collaborating on a project to generate a plant checklist for the ACT. The checklist is based on vouchered specimens held at the herbarium, which includes specimens donated by Research and Monitoring (Parks Conservation and Lands). Over time, other records will be added, primarily from specimens collected to fill gaps, rather than new species.
A definitive list of flowering plants – monocotyledons, such as grasses, and dicotyledons, such as herbs and trees – collected from the ACT will be an important reference for managers and researchers alike. In 2007 the project partners estimated that the total number of flowering plant species in the ACT is 1500.
The checklist may be expanded to include cryptogams (fungi) (about 600 species), lichens (about 405 species), liverworts and hornworts (about 107 species) and mosses (about 208 species). This inclusion would be useful in supporting research into the functional roles of fungi and other soil biota, and the implications of the reduction or loss of mycorrhizae (fungi associated with plants and that contribute to the plants through transport of minerals from soil to the plant and improving the structure of the soil). These species are important in all ecosystems but the study of them is particularly relevant to restoration of degraded or disturbed areas.
While cryptic in nature, the cryptogams are an important element of the ecosystem, providing early colonisation and subsequent stabilisation of soil crusts. They are also important in water and nutrient capture and recycling, and provide nurseries and refuges for young seedlings, other cryptogams, invertebrates and vertebrates alike. Cryptogams are made of those organisms that reproduce by spores and include the bryophytes (mosses, liverworts and hornworts), lichens and fungi (Streimann and Klazenga 2002; Lepp, Cargill and Crawford pers.comms.).
New plant record for ACT – Dampiera fusca
Members of the Australian Native Plant Society discovered Dampiera fusca in the ACT approximately 18 months after the 2003 bushfire. This species was previously only known from small populations in the Kybean Range near Nimmitabel, the Tinderry Ranges in New South Wales (south-east of the ACT) and from the Alpine National Park in Victoria. While it is likely that the 2003 bushfire enhanced germination of this plant, it has been over 30 years since the vegetation in this area was last burnt. The main population occurs in only three areas, with the numbers of plants estimated to be approximate 800–1000 in October 2006. A second smaller population, in an inaccessible location, has been identified from helicopter. The ACT Government has recently implemented a quantitative monitoring program and will continue to assess the populations.
New listings of threatened species
Since the 2003 State of the Environment Report, the ACT Minister for the Environment has accepted the recommendations of the Flora and Fauna Committee and, pursuant to the Nature Conservation Act 1980, has declared the following species to be vulnerable or endangered species in the ACT:
- Spotted-tailed Quoll (Dasyurus maculatus)
- Canberra spider Orchid (Arachnorchis actensis)
- Brindabella Midge Orchid (Corunastylis ectopa).
- Action Plan 30 (Spotted-tailed Quoll) has been published (ACT Government 2007) and management statements have been prepared for the two orchids.
Grassland Earless Dragon and other threatened grassland species
The Grassland Earless Dragon is one of the ACT's most threatened grassland species. It is known from four populations in only two locations: the Majura and Jerrabomberra valleys (a genetically different form is found near Cooma in New South Wales). The main population in the Majura Valley is located on the Military Training Area and the adjacent Canberra International Airport. In the Jerrabomberra Valley the Monaro Highway separates two populations that are located in native grassland on both leased and unleased rural land. East of the highway the population is in all probability linked to smaller populations across the New South Wales border on the Letchworth Nature Reserve and a rural property north of Jerrabomberra. Most of the population to the west of the Monaro Highway is now protected in a nature reserve. The ACT Government is proposing to develop part of the grassland habitat where Grassland Earless Dragons have been recorded (Block 17 Section 102 Symonston) as a mobile home park.
Monitoring of the two key populations of Grassland Earless Dragons at the Majura Training Area and Jerrabomberra West grasslands during the reporting period indicates that both populations have declined. Although monitoring indicates a brief increase in the Jerrabomberra West population during 2006, captures at this site are now about 30% fewer than in 2004. At the Majura Training Area monitoring indicates that the population has declined by about 75% since 2004. The sharp drop in numbers of Grassland Earless Dragons at the Majura site is of concern. It coincides with the almost complete removal of grass tussock cover over the past two years from overgrazing (by kangaroos), whereas in the Jerrabomberra grasslands, which have been only lightly grazed and still have good grass cover despite the drought, the population of Grassland Earless Dragons is several times greater than that at Majura.
The threats to continued survival of this endangered species in the ACT and the priority actions for its conservation are set out in Action Plan 28 (Lowland Native Grassland Conservation Strategy). The main threat is 'continued loss and fragmentation of its grassland habitat' through, amongst other factors, 'degradation of habitat through changed grazing intensity' and urban development (ACT Government 2005). At the end of the reporting period the loss of the cover and structure of the native grassland at the Majura Military Training Area and the Belconnen Naval Transmission Station, as a result of excessive grazing by kangaroos, had become an issue of public concern requiring active intervention by the Department of Defence, which manages both areas. Given the observed severe decline in the Grassland Earless Dragon population at Majura there is a real prospect that the main threat (degradation of habitat through changed grazing intensity) is being observed at this site. Urgent action to relieve the pressure of kangaroo grazing on this grassland followed by remedial management action to promote recovery for the grassland is needed. A greater public acknowledgement of the known and significant biodiversity values of the grassland habitat on the Military Training Area is warranted, as is assessment of the potential of the area to be protected as part of the nature conservation estate. At the end of the reporting period the Department of Defence had not announced its intentions with regard to managing the overgrazing of kangaroos at Majura Training Area.
Other grassland species affected by the decline of grass cover on land managed by the Department of Defence are the Striped Legless Lizard and Button Wrinklewort at Majura, the Ginninderra Peppercress at Belconnen, and the Golden Sun Moth and the Perunga Grasshopper at Majura and Belconnen. An underlying lack of ecological knowledge of these species and their habitat requirements is a common link with the grazing intensity by kangaroos and the survival of the grassland as a community of plants and animals.
The management requirements essential to conservation of native grassland ecosystems are not currently well understood although some scientific expertise is available in local and interstate universities. Cooperation between managers, ecologists and the community needs to improve in order to harness the available experience and to focus research and management effort on the key issues that will determine whether these highly threatened grassland communities survive as part of the ACT's natural environment.
In 2006 the ACT Government began supporting two doctoral research students and an honours student in studies designed to better inform management of grassland reptiles, invertebrates and their grassland habitats. This is a welcome initiative given the precarious state of the remaining populations of the Grassland Earless Dragon. The research involves developing understanding of the basic ecology of Grassland Earless Dragons, such as daily movement patterns, habitat use and home range characteristics. Another focus of the research is the impact of fragmentation of native grassland habitat on populations of the dragon and other grassland fauna such as invertebrates, particularly any relationship between dispersal, population genetics and the potential for dragons to recover in the long term. The ACT Government is continuing to improve methods to monitor changes in population sizes of the Grassland Earless Dragon. Such research and monitoring is vital if land set aside in nature reserves to conserve the natural environment is to be managed effectively for recovery of threatened species and ecological communities (ACT Government 2005).
Spotted-tailed Quoll (Dasyurus maculatus)
The largest marsupial carnivore on mainland Australia is the Spotted-tailed Quoll. Its distribution and populations have declined since European settlement and it is declared a threatened species in all jurisdictions where it occurs. In the mid-1800s, both the Spotted-tailed Quoll and closely related Eastern Quoll (D. viverrinus) were present in the ACT region and quolls were seen regularly in the Tidbinbilla Valley. By 1971 the Eastern Quoll was considered to be extinct on the mainland. In the ACT since the 1950s there have been 14 confirmed records (animals live or dead, hair, scats or DNA) of the Spotted-tailed Quoll. These records are widely distributed across the ACT and include three within the suburban area. Surveys conducted by an ACT Government ecologist in 2003 and 2004 recorded the species in the Gudgenby and Orroral Valleys by hair and DNA in scats and occasional sightings continue to occur across the ACT and surrounding region. In July 2006 an adult male quoll was found as road kill south of Tuggeranong. The low frequency of records in the ACT is probably due to the elusive nature of the Spotted-tailed Quoll, as well as its actual abundance (ACT Government 2005).
ACT rivers and streams provide habitat for an aquatic fauna typical of montane environments, where snowmelt and winter rainfall provide an annual flow cycle of colder water in spring and warmer, lower volume flows through the summer. The flows in the region's rivers are modified by water extraction for farm and domestic supply and to supply dams for hydroelectricity production and management of flows for irrigation in the lower reaches of the Murrumbidgee River beyond the ACT's borders.
Four species of fish and one species of crayfish found in ACT waters are listed as threatened with extinction. They are the Two-spined Blackfish (Gadopsis bispinosus); the Trout Cod (Maccullochella macquariensis); the Macquarie Perch (Macquaria australasica); the Silver Perch (Bidyanus bidyanus); and the Murray River Crayfish (Euastacus armatus) (see Table 2). Action Plans published between 1999 and 2003 are now incorporated into Action Plan 29: Aquatic Species and Riparian Zone Conservation Strategy (ACT Government 2007). Common threats to these species include altered flow patterns, thermal pollution, sedimentation of rivers and barriers as a result of river modifications, alien species which predate on young fish or carry disease or parasites, alteration to river habitat due to lack of trees or invasion of willows, and pressures from recreational use, including illegal fishing. A consequence of the 2003 bushfires has been that access to areas formerly closed to public vehicle access was opened up because of the destruction of gates. While these gates have been restored, there is anecdotal evidence of illegal fishing in the Cotter Reservoir and the Cotter River between the reservoir and Pierces Creek junction. This is of particular concern because of the potential impact on the remnant Macquarie Perch Macquaria australasica population, even though fishers in the area may be mainly targeting trout.
Action Plans for threatened fish species have highlighted the need for surveys into the distribution of the fish in the waters of the ACT and region and for regular monitoring of distribution and abundance and research into the nature of the threats and measures needed to mitigate their effects. In this reporting period, researchers made substantial progress in extending our knowledge of which rivers maintain populations of the fish and in establishing monitoring programs (see Table 2). Some research priorities have been addressed, due in part to the need for this information to monitor the impacts of water abstraction from water supply dams and the success (or otherwise) of the release of environmental flows designed to maintain the health of our rivers, and the measures needed to ensure survival and/or recovery of native fish species that have declined for the reasons described.
Significant threats to the survival of local populations of some threatened fish species remain. Threats include the planned increase in water extraction from the Cotter and Murrumbidgee rivers for Canberra's domestic supply, the proposed enlargement of the Cotter Reservoir, and the continued spread of alien species. These pressures emphasise the need for a greater body of knowledge about the biology of the affected fish species, their habitat use and their responses to more regulated patterns of river flow. Also essential to any successful program to manage rivers for both water supply and biodiversity conservation is commitment to comprehensive monitoring programs designed to highlight adverse impacts on threatened species and other important river biodiversity.
Since 2003 an encouraging start has been made to establish the required research and monitoring programs. ACT Government fish ecologists have successfully accessed funding from the Natural Heritage Trust, the Fisheries Research and Development Corporation and the ACT Government to undertake some of this work and to support some collaborative projects with the University of Canberra. Some conclusions from this research are outlined below:
Trout Cod (Blue Nosed cod) (Maccullochella macquariensis)
A study has shown that re-establishment of cod populations based on release of on-grown two-year old fish is not an immediate and straightforward alternative to the existing practice of stocking fingerlings into rivers. It is also evident that some large individuals can travel tens of kilometres. The pattern of Trout Cod remaining in small river reaches for extended periods, punctuated by occasional large-scale movement, has implications for fisheries managers and requires improved selection of sites for re-establishing the species and rehabilitating habitat. Research has demonstrated that re-establishment of ecologically sustainable fisheries of Australian freshwater cod populations is unlikely to achieve broad-scale success without commitment to more informed recovery programs than those based primarily on stocking of fingerlings.
Macquarie Perch (Macquaria australasica)
An investigation into possible sources of predation on a remnant population of the endangered Macquarie Perch in the Cotter Reservoir has not resolved whether predation from introduced species, including brown trout and rainbow trout, is significant. Juvenile Macquarie Perch do not reside in the parts of the reservoir from which most trout were actually sampled in the current study. However, predation by cormorants and/or trout is possibly extreme and may result in elimination of young-of-the-year Macquarie Perch from the predominantly simplified habitat in the upstream third of the reservoir.
Murray River Crayfish (Euastacus armatus)
Fitting radio-tags to individual Murray River Crayfish to follow their activity and habitat use over several days and nights proved successful and is likely to be useful for measuring short-term changes in behaviour in response to pulse disturbances, including environmental flows.
A sustained effort to maintain survey and monitoring programs and to expand the research effort will be needed in coming years if recovery of the threatened fish species and the Murray River Crayfish is to be successful. Pressure on the populations of these species in the ACT and the rivers entering the Territory is unlikely to decrease in the near future. The ACT's capacity to manage its rivers and their biota depends, to a large degree, on how well managers are supported by improved knowledge based on well-directed and sound scientific research.
|Strategy||Progress over reporting period|
|Survey of the upper Murrumbidgee River catchment (TSBF, TC) and ACT rivers (MP, MRC)||Surveys of major streams completed before this reporting period.
TSBF: Single small population located in Murrumbidgee River above Yaouk. Population previously reported from below Yaouk not located.
TC: Species not detected away from stocking sites.
MP: Good populations upstream of Cooma, small population at Michelago. Population in Goodradigbee River now considered not viable. Species recorded in extremely low numbers from one Paddys River site near Cotter River confluence. Not recorded in Lower Queanbeyan River, but occupies 15 km of river upstream of Googong Reservoir. Waterfall at Silver Hills blocks upstream movement.
MRC: A survey was undertaken in 2005.
|Monitoring of distribution and abundance|
|Establish or continue monitoring programs for each species.|
|TSBF: Cotter River catchment: Encourage monitoring of populations in areas of New South Wales adjacent to the ACT. Potential streams include Goodradigbee River, Micalong Creek, Mountain Creek, Murrumbidgee River near Yaouk.||TSBF: Program in place, including New South Wales locations. Monitoring recorded significant decline in the species following 2003 bushfire and substantial recovery at most sites in 2004. Impacts of environmental flows on blackfish recruitment monitored in 2001, 2003, 2005.|
|TC: Continue monitoring program for the two ACT stocking sites, and monitor in Murrumbidgee River.||TC: Annual monitoring undertaken at both sites. Angle Crossing: Good survival of stocked fish but unable to catch individuals more than 3 years old; dispersal downstream detected in 2000. Bendora Reservoir: Catch rate low as it is more than 15 years since stocking, and fish are thought to be largely beyond reach of sampling equipment. Juvenile fish (estimated 1–2 years old) collected in 2004, indicating a successful breeding event. Biennial monitoring of Murrumbidgee River undertaken. Downstream dispersal from Angle Crossing detected in 2000 but not in 2002 or 2004.|
|MP: Establish a monitoring program for the Cotter, Murrumbidgee and Queanbeyan river sub-populations of Macquarie Perch.||MP: Monitoring program implemented from 2001 including Queanbeyan, Cotter, Goodradigbee and upper Murrumbidgee rivers: 2001 numbers considerably lower than previously; 2003, 2004 and 2005 failed to record species at Goodradigbee River site and no recruitment in the Queanbeyan River. Adult population now below reliable detection limits in Queanbeyan River (suspect drought impacts). Spawning and recruitment were successful in the Cotter River under drought modified environmental flows in 2004–07. Increased monitoring undertaken, related to drought affected environmental flow regime.|
|SP: Murrumbidgee River in the ACT.||SP: No individuals detected in Murrumbidgee River.|
|MRC: Establish a monitoring program for Murray River Crayfish at representative sites in the ACT.||MRC: Monitoring program in place covering 10 sites in the Murrumbidgee River. Recorded in the Murrumbidgee River with individuals detected at several sites in 2000 and 2002; 2003 program postponed due to change of priorities following bushfires.|
|TSBF: Encourage research into key information gaps, including longevity, spawning requirements, effects of alien species, population genetics, habitat management (including preparing for an expanded Cotter Reservoir). Cooperate with other agencies in a coordinated study of the population genetics of the subpopulations of Two-spined Blackfish in the Canberra region, including those in the Cotter, Goodradigbee, Goobarragandra and upper Murrumbidgee rivers and Mountain Creek.||TSBF: Research projects completed into effects of environmental flows, the genetic relationships between populations in eastern Australia and on potential impacts of thermal pollution from impoundments on growth rates (for details of reports see Action Plan 29).|
|TC: Encourage research into key information gaps including breeding requirements, effects of alien species, habitat management, dispersal, and stocking strategies.||TC: Experimental habitat rehabilitation established at Tharwa. Projects commenced into movements of wild fish and hatchery reared Trout Cod in Cotter River and Murrumbidgee River at Narrandera (2003–05), and fine scale spatial and temporal movements and habitat use by Trout Cod in Cotter River.|
|MP: Encourage research into key information gaps including resolution of the taxonomic status (inland and coastal populations), effects of alien trout and Redfin Perch, and effects of Epizootic Haemotopoeitic Necrosis (EHN) virus in the wild.||MP: Experimental habitat rehabilitation established at Tharwa. Projects completed into predicting suitable habitat, the impacts of environmental flows, and investigating the movement requirements in Cotter Reservoir and lower Cotter River. An important river reach for breeding identified immediately upstream of Cotter Reservoir. Genetic study commenced to resolve taxonomic issues.|
|SP: Encourage research into key information gaps, including effects of Carp and Redfin Perch and effects of EHN virus on wild fish populations. Encourage investigations into identification of the genetic composition of Lake Burrinjuck populations of Silver Perch.||SP: No research specific to Silver Perch commenced.|
|MRC: Encourage research into key information gaps including habitat management, effects of alien species and age at first breeding.||MRC: Projects on Murray River Crayfish completed in 1999 and 2005.|
Key: TSBF = Two-spined Blackfish; TC = Trout Cod; MP = Macquarie Perch; SP = Silver Perch; MRC = Murray River Crayfish
Source: Data provided by Research and Monitoring, TAMS
Eastern Grey Kangaroos
Between 1995 and 1997 the ACT Kangaroo Advisory Committee (KAC) prepared three reports that reviewed kangaroo management on public land (KAC 1997), rural land (KAC 1996a) and in captive situations (KAC 1996b) in the ACT.
The Natural Resource Management Advisory Committee has monitored the implementation of the recommendations contained in the three reports prepared by the KAC. This committee last received a report in respect of implementation of these recommendations in February 2007.
Successive ACT governments have adopted the KAC recommendations as the policy framework for managing kangaroos in the ACT. One recommendation found in the KAC reports is that an overall kangaroo management plan be developed for the entire ACT. This kangaroo management plan is now in the early stages of being prepared. This plan will incorporate those recommendations from the KAC reports which have continuing relevance and will provide a basis for kangaroo management in the ACT in the future.
In response to several recommendations in the KAC reports and the general theme of these reports, researchers identified the need to quantify the main influences on kangaroo population dynamics in the ACT, as a foundation for management strategies. To meet that need, the ACT Government sponsored one of its officers to undertake post-graduate research with Professor Jim Hone, at the University of Canberra's Institute for Applied Ecology. The research into the dynamics of the Eastern Grey Kangaroo (Macropus giganteus) populations and their food supplies in temperate grasslands ran from 2001 to 2006. The research results will greatly increase the ACT Government's capacity to manage kangaroos in the variety of locations and environments in which they are found.
Some important findings of this research include:
- the dynamics of kangaroo populations in temperate Australia (including the ACT) differ significantly from those in the semi-arid zone where all previous research on kangaroo population dynamics has been conducted
- more complex models are needed to represent the dynamics of temperate kangaroo populations
- Eastern Grey Kangaroo populations in temperate grasslands, being much higher per unit area, are capable of greater effects on herbage mass than are semi-arid kangaroo populations, and can provide high grazing pressure for more sustained periods
- temperate kangaroo populations qualify as 'ecosystem engineers' as defined by Jones and colleagues (1997) and Wilby and colleagues (2001), because the ecological changes they induce, have a strong influence on numerous other organisms, such as birds (Neave and Tanton, 1989)
- Eastern Grey Kangaroos are smaller, eat less and are more numerous than has generally been supposed
- in kangaroo populations at equilibrium with their food supply, winter starvation of sub-adults is common, it is the most important demographic factor, and in some places it provides a rare opportunity for public education about kangaroo ecology and management
- in the temperate environment encountered in the ACT region Eastern Grey Kangaroos continue to produce young-at-foot in drought years in spite of food shortage or high density
- in stable, food-limited populations, the combination of high fecundity and winter mortality of sub-adults, results in strong ecological resilience against predation, parasitism, shooting and fertility control
- in the ACT region the Eastern Grey Kangaroos do not give birth continuously all year
- kangaroo shooting in southeastern Australia can be timed to minimise the number of young that are orphaned at a vulnerable age.
The abundance of Eastern Grey Kangaroos has increased strongly during the last half century in the ACT. Numerous anecdotal reports confirm the change, including those reported by the ACT Kangaroo Advisory Committee. Populations increase by normal exponential growth, so the change on any particular site is typically slow at first, then rapid, and has often caught managers unprepared. In some cases a 'herbivore eruption' has resulted, best evidenced in counts at Googong Foreshores from 1980 to 2004. The crash phase of a herbivore eruption is a time when both the vegetation and the kangaroos are put under great stress.
A broad range of ecologists now agree that modern high-density populations of Eastern Grey Kangaroos have overgrazed some of the remaining fragments of the original Natural Temperate Grassland to the point that the endangered ecological community and its many threatened species, such as Grassland Earless Dragons, are affected. An example is the largest area of Natural Temperate Grassland in the ACT, on the Majura Training Area. However only a few years ago, this was not apparent, even to some ecologists.
Kangaroo grazing is now seen as a central process in the Natural Temperate Grassland ecosystem. Some level of kangaroo grazing (or grazing by another large vertebrate) is essential for biodiversity maintenance, so Eastern Grey Kangaroos are a 'keystone species'. Complete removal of kangaroos (without another large animal to replace them) would probably lead to a series of extinctions. On the other hand, long periods of unrelieved heavy grazing are also a threat to biodiversity.
Long-term monitoring by Parks Conservation and Lands shows that the Grassland Earless Dragon population at Majura has been devastated due to loss of its habitat by heavy kangaroo grazing. In the mid-1990s when there was abundant grass at Majura Training Area, the catch-rate of Grassland Earless Dragons was 154% compared to a reference site on the 'Woden' sheep grazing property. Following the loss of the grassland structure and cover, the catch rate at Majura in 2007 was 3% to 12%.
Grasslands and grassland-reliant species, such as Grassland Earless Dragons, must have evolved in the presence of some level of kangaroo grazing and this knowledge has led some commentators to dismiss the possibility of native species affecting other native species. In fact there are many examples in the scientific literature, and more importantly, the evidence in the ACT is clear. The explanation may be found in the impact of modern changes such as loss of predators and habitat fragmentation. Judging from other predator–prey systems around the world, and where dingoes are still present with kangaroos in Australia, the missing predators probably strongly moderated the kangaroo grazing pressure. Where grazing was intense, in the original system of extensive grasslands, animals and plants would have been able to re-colonise the denuded patch, but in the modern context, habitat fragmentation prevents that. Now kangaroo grazing can severely defoliate a relatively isolated area of native grassland, such as is found at the Majura Training Area, for years in succession with an accompanying impact on grassland-dependent species.
Because predators such as Thylacines or dingoes cannot be re-introduced, shooting or fertility control (when it becomes feasible) may be important mechanisms for conserving the full range of remaining elements of the original grassy ecosystems.
Data sources and references
TAMS Territory and Municipal Services, Research and Monitoring
ACT Government 2005, Action Plan 28, Vision Splendid of the Grassy Plain Extended: ACT Lowland Native Grassland Conservation Strategy, Arts, Heritage and Environment, Canberra 2005 available at <http://www.tams.act.gov.au/__data/assets/pdf_file/0011/13016/actionplan28visionandcontents.pdf>
ACT Government 2007, Action Plan 30, Spotted-tailed Quoll (Dasyurus maculates): A vulnerable species, Arts, Heritage and Environment, Canberra 2005 available at <http://www.tams.act.gov.au/__data/assets/pdf_file/0006/13020/actionplan30spotted-tailedquoll.pdf>
ACT Kangaroo Advisory Committee 1996a, Living with Eastern Grey Kangaroos in the ACT – Rural Lands, First Report to the Minister for the Environment, Land and Planning, ACT Government, Canberra 1996 available at <http://www.tams.act.gov.au/__data/assets/pdf_file/0004/13837/actkangarooadvisorycommitteereport1pdf.pdf>
ACT Kangaroo Advisory Committee 1996b, Living with Eastern Grey Kangaroos in the ACT – Kangaroos in Captivity in the ACT, Second Report to the Minister for the Environment, Land and Planning, ACT Government, Canberra 1996 available at <http://www.tams.act.gov.au/__data/assets/pdf_file/0017/13823/actkangarooadvisorycommitteereport2pdf.pdf>
ACT Kangaroo Advisory Committee 1997, Living with Eastern Grey Kangaroos in the ACT – Public Land, Third Report to the Minister for the Environment, Land and Planning, ACT Government, Canberra 1997 available at <http://www.tams.act.gov.au/__data/assets/pdf_file/0010/13051/actkangarooadvisorycommitteereport3pdf.pdf>
Australian Biological Resources Study, Checklist of Australia liverworts and hornworts, Department of the Environment and Water Resources, available at <http://www.anbg.gov.au/abrs/liverwortlist/liverworts_intro.html>
Australian Biological Resources Study, Checklist of the lichens of Australia and its island territories, Department of the Environment and Water Resources as at 13 June 2008, available at <http://www.anbg.gov.au/abrs/lichenlist/introduction.html>
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