National recovery plan for the Wedge-tailed Eagle 1998-2003
Phil Bell and Nick Mooney
ISBN 0 724 66216 2
We wish to thank Raymond Brereton, Bill Brown and Robbie Gaffney for advice and assistance in preparing this recovery plan. We also thank the Natural Heritage Trust for providing funds through the Endangered Species Program to prepare this plan.
- Australasian Raptor Association, a special interest group of Birds Australia
- Department of Environment and Land Management
- Environment Australia
- Forest Practices Code
- Forest Practices Officer
- Forestry Tasmania
- Geographic Information System
- Hydro-electric Corporation
- Private forestry companies
- Tasmanian Regional Forest Agreement
- Parks and Wildlife Service, Tasmania
- Forest Practices Plan
Current Species Status
The Tasmanian wedge-tailed eagle Aquila audax fleayi is considered to be critically endangered by the Endangered Species Advisory Committee based on IUCN (1994) criteria, listed as endangered under Schedule 1 of the Commonwealth Endangered Protection Act 1992 and vulnerable under Schedule 4 of the Tasmanian Species Protection Act 1995. Being a top-order predator, the species has naturally low population densities. Combined with Tasmania's small size this gives a small overall population of about 220 territories, most of which are occupied by pairs; translating to a total population less than 1000 individuals.
Habitat Requirements and Limiting Factors
The eagleis found throughout mainland Tasmania and on nearby, large islands. It builds stick nests in tall eucalypt trees in areas of predominantly old-growth eucalypt forest of greater than 10 hectares in size, usually on slopes sheltered from locally prevailing winds. The species is highly territorial and, given sufficient habitat, active nests are evenly dispersed. Nearest-neighbour distances vary regionally but are usually in the order of 9-12 km. Foraging occurs in most terrestrial habitats.
Approximately 80% of known nests occur on private land and State Forest, land particularly prone to disturbance and severe alteration by human development. Disturbed nests are significantly less productive than undisturbed nests (in that a lower proportion produce nests) and each year more nests can be categorised as disturbed. As a result of disturbance statewide breeding success continues to decrease. When combined with a continued high rate of human induced mortality from persecution (shooting, trapping and poisoning), electrocution and collisions with vehicles, wires and fences and an apparent lack of adult 'floaters' a reduction in the total population can be inferred. Human induced mortality, particularly of adults may have also contributed to a reduced breeding success by reducing the mean age of the breeding population with a probable reduction in experience and competence.
Recovery Plan Objectives
To achieve down-listing of A. a. fleayi from endangered to vulnerable within five years of the implementation of this plan by maintenance of population and reduction of threats.
Increase population size by increasing the number of pairs that produce young and reducing human induced mortality.
- Increase the proportion of nests found prior to logging and other land development operations.
- Increase the number of nests fledging young.
- Complete nest management agreements for 30 nesting territories on private land.
- Reduce human induced mortality.
- Find nests on private land and State Forest.
- Protect nesting habitat on private land and State Forest.
- Monitor breeding success and abundance.
- Promote conservation of eagles to land owners/managers.
Estimated Cost of Recovery (1997 prices in $000s/year)
Protection and management of A. a. fleayi nests and associated habitat will have benefits for the conservation of old growth eucalypt forest which supports a high diversity of fauna and flora via an 'umbrella' effect. As a top-order predator the eagle may play an important role in population regulation and genetic fitness of its prey species. Conservation of A. a. fleayi will also have positive flow-on effects for the conservation of the white-bellied sea-eagle Haliaeetus leucogaster, although not yet formally threatened (but listed as threatened in nearby Victoria) it is a species that is suffering increasing conservation problems.
1.1 Description of Species
The Aquila are large eagles that have long, rounded wings with deeply emarginated tips, very strong legs and claws, 'ear shaped' nostrils and legs feathered down to the feet. Although not the heaviest, the wedge-tailed eagle is the largest Aquila, A. a. fleayi being the largest and heaviest wedge-tailed eagle (Marchant & Higgins 1993).
Total body lengths of A. a. fleayi are 100 to 110 cm, wingspans 1.9 to 2.3 m and weights 3.5 to 5.5 kg. Females are larger (particularly longer with a much larger beak) and at a weight difference of about 15%, reversed sexual dimorphism is low to moderate. At fledging, juveniles are tawny brown with a blonde nape and dark flight and tail feathers, plumage darkening with successive moults until after 20 years old the birds appear almost black. The bases to adults' primaries are pale silver, giving a distinct 'window' when viewed from underneath. A. a. audax is sexually mature at 4-6 years old, the same probably applying to A. a. fleayi (Marchant & Higgins 1993). Adult birds, especially males, are dark, sooty brown with a reddish-golden nape. Rarely does A. a. fleayi obtain the near black plumage of old individuals of A. a. audax (e.g. Meredith 1990).
Territorial advertising is mainly by visual display, usually aerial. Outside the breeding season, wedge-tailed eagles are usually silent, though they produce a range of specific, rather gentle calls. A. a. fleayi is usually found singly, in pairs or as a family group but under some conditions feeds communally. Co-operative hunting also occurs in the species (Marchant & Higgins 1993).
1.2 Distribution and Abundance
The wedge-tailed eagle is Australia's only Aquila and A. a. fleayi is an endemic subspecies of Tasmania. The eagles are true 'landscape predators' and have one of the widest distributions of Tasmania's terrestrial birds, being found on large offshore islands, along the entire coast and inland over the central highlands.
Adults are resident all year although their patterns of use of home ranges appears to change seasonally. Tasmania's wedge-tailed eagles have less genetic variation than their mainland conspecifics (Groth et al. in prep) and may have been genetically isolated for the 8,000 to 10,000 years since the last trans-Bassian land bridge. Like all Aquila they are reluctant to cross large stretches of open water.
Being a highly territorial, top-order predator, wedge-tailed eagles have very large home ranges, and where suitable habitat exists, evenly dispersed territories. Thus they are only found at low nesting densities. Estimated densities of A. a. fleayi range from a maximum of one pair per 20-30km2 in a mosaic of dry sclerophyll forest and fertile open habitats in lowland eastern and northern Tasmania, to a minimum of one pair per 1200km2 in highland western and south-western Tasmania (Mooney unpubl. data). Their general shyness of humans compounds this phenomenon (they do not nest where human densities are high) and Tasmania has only about 220 nesting territories [(Mooney (in press), refined from the earlier, conservative estimate of about 140 territories in Mooney & Holdsworth (1991)]. Not all territories are occupied by two adults and replacement times for adults 'lost' from territories seem excessive (sometimes more than 6 months, Mooney unpubl. data) suggesting a dearth of extra-territorial 'floaters' and an adult population of less than 440. Given likely minimum mortality rates of about 50% for juveniles, 30% for other immatures and 5% for adults, this infers a total population of less than 1000.
1.3 Population Trends
There are no historical measures of population size in Tasmania although anecdotal records suggest that A. a. fleayi was widespread but uncommon also at the time of European settlement (Mooney & Holdsworth 1991). This eagle may have later benefited from rabbit plagues but there was consequent secondary poisoning from rabbit control programs and coincident, heavy persecution from stock owners.
Breeding success (as measured by the number of pairs producing at least one young) has decreased to the point where about 95 pairs are successful each year in Tasmania (Mooney 1998). In 1989, 69% of territories where the active nest or all nests were known produced at least one egg, and 53% were considered to be successful in fledging young (Mooney & Holdsworth 1991).
Although problematic in their interpretation, road counts of A. a. fleayi undertaken between 1978 and 1997 suggest that the total population is either stable or slowly decreasing (Mooney unpubl. data). Importantly, the proportion of immatures seems to be decreasing (Mooney unpubl. data). If true, these trends (slow decrease in population size, decreasing proportion of immatures and a dearth of adults as 'floaters') could be explained by a decreasing total population due to a lack of recruitment. The obvious risk is an accelerating population decrease as adults die and are not replaced. Such a decrease could be displaced in time from the period of reduced recruitment since adult mortality is low and the birds are long-lived. However, the decrease may not be sudden (i.e. a 'crash') because low productivity is not homogeneous across the state (some areas could be 'topping up' other areas).
1.4 Nesting Habitat
A. a. fleayi nests in a range of old-growth native forests. Most nest trees are situated in multi-aged communities where most of the trees are old-growth. Over 50% of known nests occur in tall open forest above an open or closed forest understorey (Mooney & Holdsworth 1991; Brown & Mooney 1997). A. a. fleayi is dependent on forest for nesting, unlike A. a. audax which often nests in isolated trees, even occasionally on cliffs (Crawford 1987; Marchant & Higgins 1993). However, the range of situations in which wedge-tailed eagles nest in Tasmania reflects a latent flexibility i.e. extremes exist from almost pure rainforest to almost isolated eucalypts in acacia forests.
Ninety five percent of A. a. fleayi nests occur in emergent trees in old-growth eucalypt forest. Nest trees are among the largest in height and girth at the nest site (the area within a radius of 50 m of the nest tree) and are usually on sloping ground with an aspect sheltered from cold spring winds. They are typically positioned between the lower and mid-slopes on the leeward side of a ridge sheltered from prevailing winds, where the height of the nest tree is lower than the ground level of the top of the ridge (Mooney & Holdsworth 1991). The high degree of consistency of these parameters and availability of adequate mapping resolution provide the basis for the development of predictive models of nesting habitat (Brown & Mooney 1997).
Territories contain up to five alternate nests, usually constructed within 200m of each other, but sometimes over 1km apart where habitat is locally restricted. Although several nests in a territory may be lined, one nest is usually favoured for breeding each year and generally re-used until breeding fails. When not breeding, adult A. a. fleayi visit nests to perch, eat prey, or renovate nests, indicating a year round attachment (Mooney 1988). Nest sites are traditional with some nests known to be used for over 50 years.
Nests comprise an accumulation of large dead sticks with a shallow depression on top which is lined with live twigs, leaves (where available from black peppermint Eucalyptus amygdalina) and bark (Marchant & Higgins 1993). The diameter of nests range from 0.86 to 2.8 m (volume from 1.5 to 5 m cubic meters) and nests are located at heights between 54 and 80 per cent of the nest tree height, almost always within the canopy even if in a emergent tree. In some locations, competition with white-bellied sea eagles for nest sites is intense (e.g. Terry 1996). This problem seems to be increasing as options for nesting decrease. Wedge-tailed eagles are usually dominant but may themselves not be able to breed (because of disturbance levels). Thus, even the more disturbance tolerant white-bellied seas eagles do not breed.
1.5 Life History and Ecology
Wedge-tailed eagles generally pair for life and when courting and pair-bonding, perform spectacular aerial displays. Resident, adult eagles stay together throughout the year and although they may be seen at any time of year perching close by and allopreening etc., courtship proper does not start until late June. From this time there is a gradual increase in aerial displays and nest repairing behaviour which peaks in late August. During August, the month prior to egg laying, the nest is liberally adorned and lined with greenery. This behaviour continues throughout breeding and may even be exhibited by single adults in territories.
The median laying date is usually 1st September. One to two eggs (usually one) is laid in late August or early September. In contrast, A. a. audax often lays two and sometimes three eggs between June and August (Cupper & Cupper 1981). Eggs are whitish-grey with a few brown spots, rounded to oval in shape and approximately 73 x 58 mm in size. The female incubates the eggs for 43-45 days and during this time is fed by the male. For the first few weeks after hatching the chick is fed by the female. Fratricide has not been recorded in A. a. fleayi but there has been no specific study. In any case, the rarity of even two egg clutches means sibling aggression could rarely be demonstrated. Chicks take up to 90 days to fledge (Cupper & Cupper 1981, Mooney unpubl. data). By six to eight weeks of age the chick is capable of feeding itself and both parents bring food direct to the nest. Adults however, may continue to feed them for many weeks.
After fledging A. a. fleayi remain near the nest for several weeks. Juveniles are dependent on their parents for food for at least three months and may accompany parent birds until the next breeding season.
Wedge-tailed eagles prey and scavenge on a wide variety of fauna including fish, reptiles, birds and mammals (Starker Leopold & Wolfe 1970). Most prey weigh 25% or less of the eagle's body weight though wedge-tailed eagles are capable of killing prey several times their own weight (e.g. Meredith 1990).
Hunting is usually initiated from a perch though most attacks are unsuccessful. Less common methods of hunting include slow quartering at 10-20m above the ground and, occasionally, diving from higher altitudes. Most prey is captured on the ground, during the day and eaten where it is caught, except during breeding. The species favours open areas for hunting and has been recorded hunting over most Tasmanian terrestrial habitat types. The long tail of the wedge-tailed eagle allows hunting in forest. Eagles, for instance find brush-tail possums Trichosurus vulpecula by flying slowly amongst the canopy, perching and examining shallow hollows in trees (Mooney pers. obs.).
In rural Tasmania, rabbits, hares and cats contribute to 45%, wallabies, possums, echidnas and wombats 30%, birds 10%, sheep and goats 7.5% and reptiles 5% of the prey items eaten by A. a. fleayi. Carrion is a major food source, particularly for inexperienced, immature birds and for all birds during winter. However, carrion is not known to be fed to nestlings. Wedge-tailed eagles are one of the few natural predators to regularly take feral cats and feral goats.
Immature A. a. fleayi suffer a naturally high mortality rate and usually die from diseases related to starvation due to poor hunting skills (Mooney & Hunt 1983). As they rely heavily on carrion, including domestic stock, immatures are more susceptible to persecution by stock owners. From literature on similar species (e.g. Newton 1979), natural survival of adults should be approximately 95% per year, juveniles approximately 50% and other immatures approximately 70%. However, in excess of 35% of first year birds may be killed by persecution (shooting, trapping, or poisoning) alone. Over 50% of incapacitated and dead A. a. fleayi (n=174) collected between 1980 and 1995 were immatures (Mooney in press).
A. a. fleayi is sensitive to pindone, a rabbit poison used in Tasmania, and secondary poisoning could occur after consumption of poisoned carcases (Martin et al. 1994). Other raptors have been killed by baits using alpha-chlorolase for control of forest ravens Corvus tasmanicus and such control can only be a threat to wedge-tailed eagles. Although anecdotal reports claim that wedge-tailed eagles have died from eating carcases of animals poisoned with 1080 (sodium monoflouroacetate), no post mortem results have confirmed this (over 20 have been carried out on eagles dying from unknown causes including several suspected 1080 kills). Eagles show a high physiological tolerance to 1080 (McIlroy 1984) and poisoning programmes carried out according to legal guidelines are unlikely to directly harm them. However, indirect harm might occur from the reduction of the prey, the intention of the poison. Nestlings may have a lower tolerance, but since they are fed live-caught prey, the potential for their exposure is lowered. A few wedge-tailed eagles die from lead poisoning after consuming prey containing lead shot (Mooney 1986).
Wedge-tailed eagles were heavily persecuted throughout Australia for many decades (Starker Leopold & Wolfe 1970) on the presumption that they kill sufficient lambs and ewes to cause economic harm to the sheep industry. However, research on mainland Australia has shown that the number of lambs eaten by eagles is less than 5% of the total number born (Beckmann 1988). Given that the average lambing loss is about 20-30% (from mismothering, exposure, starvation, difficult births and predation) (Dennis 1964), and lambs eaten by eagles include many already dead or dying, the number of healthy lambs killed by eagles is probably very small.
There is a small (illegal) market for mounted eagles and several are killed for this purpose each year.
A. a. fleayi continues to be persecuted by stock owners in Tasmania. Vandals also contribute to the mortality rate, shooting eagles for no apparent reason (e.g. Mooney & Hunt 1983). Considering likely numbers of birds in the total population and dead eagles that come to the attention of PWS, a minimum of 5% of adults and 35% of immature eagles are illegally killed by persecution alone each year (Mooney unpubl. data).
Electrocution from power lines and installations has been responsible for number of deaths of A. a. fleayi in recent years. A study was initiated by PWS, ARA and HEC in 1996 to assess avian mortality associated with power installations and a mitigation program is being implemented by HEC (Hess 1996). Further rural-residential development using exposed wires/insulators can only further add to this problem.
Collision with vehicles, overhead wires and fences may also be an important component of mortality and the former may be biased towards adult females as they show a greater reluctance to flush from carrion (Mooney & Hunt 1983). Continued road improvement (higher sustained road speeds) can only add to this problem.
1.6 Reasons for Conservation Status
A. a. fleayi was considered to be critically endangered by the Endangered Species Advisory Committee in 1996, based on IUCN (1994) criteria, and is currently listed as endangered under Schedule 1 of the Commonwealth Endangered Species Protection Act 1992 and vulnerable under Schedule 4 of the Tasmanian Threatened Species Protection Act 1995.
Major reasons for the current conservation status of A. a. fleayi are:
- A decline in the breeding success of A. a. fleayi as a result of disturbance of breeding birds. Medium and high levels of disturbance during nesting such as forest harvesting and roading, building amongst forests and intensive recreation can dramatically reduce the success of breeding birds. Rural-residential development is of particular concern since it is probably irreversible disturbance.
- A decline in the breeding success of A. a. fleayi as a result of a continuing loss of nesting habitat. Clearing of old growth eucalypt forest for agriculture, forestry and housing has destroyed nests and reduced habitat available for breeding. Eighty percent of known nests occur on private land and State Forest where they are susceptible to forest clearance. Of the estimated 220 or so territories only about 95 actually produce young. A number of territories are occupied by only one adult. Several territories have no secure nest habitat remaining.
- A small breeding population. There are about 95 successfully breeding pairs and a total population of less than 1000.
- A decline in the number of mature individuals is inferred from long replacement times.
- A possible decline in population as evidenced from road counts.
- An unnaturally high mortality of A. a. fleayi as a result of persecution (illegal shooting, trapping and poisoning), electrocution and collision (with vehicles, fences and wires). This may have reduced the mean age of breeding birds by allowing younger, inexperienced birds to obtain territories, evidenced by territories often being held by immatures. A decline in the mean age of breeding birds (i.e. experience) may further reduce breeding success.
1.7 Existing Conservation Measures
A. a. fleayi is wholly protected under the National Parks and Wildlife Act 1970 and the Threatened Species Protection Act 1995 which prohibit the taking, possession, buying and selling of wedge-tailed eagles (or products thereof) except under special permit.
Approximately 20% of A. a. fleayi territories are centred on designated reserves such as State Reserves, Conservation Areas and Forest Reserves. Relative to the size of territories, most of the latter are small and fragmented. Even in total, they are arguably not sufficient for conservation of the subspecies, containing perhaps 50 nest sites, not all of which are secure (some are disturbed).
Under the Forest Practices Act 1985, the Forest Practices Code (Forestry Commission 1993) provides a set of standards for the protection of threatened fauna during forest operations. Under the Act, Forest Practices Plans must be prepared for forest harvesting operations. Conservation of A. a. fleayi during forest operations is guided in general by the FPC and specifically by the Threatened Fauna Manual for Production Forest (Jackson & Taylor 1994; review in progress). The manual details management recommendations for A. a. fleayi nests which include retention of habitat, limitations on disturbance during the breeding season, encourages pre-logging surveys and appropriate responses to the discovery of nests during logging operations. The manual also provides a protocol for land managers to gain information on the location of nests on State Forest and private land.
Concerns for the long term viability of A. a. fleayi were first raised in the 1970's with the onset of the export woodchip industry. At that time, nests were usually discovered during logging operations and advice for conserving nests was beginning to be sort from PWS. A program was subsequently undertaken by PWS to develop recommendations for conserving nesting habitat in production forest (Mooney 1988a). Protocols and prescriptions for conservation management were then incorporated in the FPP process.
Surveys of the breeding success of A. a. fleayi were initiated by PWS in 1983, and as additional information was accumulated, recommendations for conserving nesting habitat were further refined. In 1988, a Tasmania wide survey of breeding success was undertaken (funded by PWS, private donations and the National Estate Grants Program) and a set of recommendations, essential for protecting nest sites, was published (Mooney and Holdsworth 1991).
A recovery plan for A. a. fleayi was prepared in 1992 (Gaffney & Mooney 1992) and subsequently funded through the Australian Nature Conservation Agencies' Endangered Species Grants Program. The aim of the recovery plan was to increase the breeding success of A. a. fleayi by reducing disturbance and destruction of nesting habitat, and reduce persecution by increasing public awareness. A National Wedge-tailed Eagle Recovery Team was formed in 1993.
A large number of pre-logging nest searches have been conducted since the preparation of the previous recovery plan. These searches have been funded by FT, PWS and PFC and have sometimes used volunteers, such as from the ARA. FT, PFC and PWS have provided funding assistance for nest searches and PFC have used incentive schemes for reporting of nests in advance of logging operations.
In 1996, the HEC, ARA and PWS initiated a study to assess the extent of bird interactions and mortality associated with power installations and develop effective solutions for mitigation. An Avian Action Plan was subsequently prepared and is currently being implemented by HEC (Hess 1996).
Mooney and Taylor (1996) reviewed the value of nest site protection (i.e. the retention of the nest tree, a surrounding buffer and distraction of disturbance during breeding), in ameliorating the effects of forestry operations on A. a. fleayi. They found that the implementation of protection measures for nest sites markedly improved breeding success of pairs subject to disturbance, either by their remaining at the nest site and successfully raising young or by being more successful at fledging young elsewhere within their territory. Importantly, there was a tendency for eagles to eventually return to disturbed nests that were conserved; it can be argued that these nests were in areas preferred by the eagles.
A model for predicting A. a. fleayi nesting habitat was initiated by PWS (Mooney & Holdsworth 1991) and developed into a means for prioritising areas to be searched for nests (Mooney 1996). Considerable further refinement occurred as part of the Tasmanian RFA process (Brown & Mooney 1997). This model has potential application to the recovery process by providing an efficient method for identifying high probability nesting habitat. Although so far only developed for a single region the model provides a foundation for application in other regions. The ultimate development of modelling, where nearest-neighbour distances are applied over habitat to give highly likely sites may only be feasible for finding all nests where eagles have not been badly disturbed (and already moved from nesting places). Moreover, up to date information on activity of nests is needed for accuracy.
1.8 Past and Ongoing Recovery Actions
An increase in the breeding success of A. a. fleayi on private property was pursued through the establishment of individual agreements and management plans. Following initial liaison with land owners and a review of the action by the recovery team the proposed 'agreement' was modified to a set of 'guidelines'. Generic and several site specific guidelines were then prepared. Throughout Tasmania about 60 land owners were contacted, on-site meetings were held with about 40 land owners and verbal agreements were received from about 20 land owners. Whereas the majority of the land owners recognised the value of implementing the guidelines there was a reluctance to make a stronger commitment in the form of signed acknowledgments. This process, however, provided an excellent means of education (of all parties).
Implementation of the action has been protracted and ineffective in terms of the recovery objectives. Nonetheless, protection of nesting habitat remains fundamental to the recovery process and a greater land owner commitment is necessary to ensure long term security of nests on private land remembering that in the long term, under the current legislative regime, private land cannot provide great security. It is recommended that the action be ongoing but incorporated in the program recently established to protect Priority Species (forest dependent species listed under the Threatened Species Protection Act 1995) as part of the Tasmanian RFA (November 1997) and modified to make use of provisions for Land Management Plans and Agreements under the Threatened Species Protection Act 1995.
The genetic 'fitness' of A. a. fleayi was investigated by comparison of the genetic variability within the subspecies with that shown by A. a. audax on mainland Australia. Blood samples were collected from 14 A. a. fleayi and 19 A. a. audax from various localities in Tasmania and mainland Australia, respectively. DNA fingerprinting was analysed among individuals, within subspecies and between subspecies. Preliminary results indicate a significantly greater genetic similarity among A. a. fleayi than A. a. audax specimens. Although the results suggest some loss of genetic diversity within the Tasmanian subspecies it is not beyond what would be expected for an isolated population. The results of the DNA analyses and their implications for the recovery process will be published shortly (i.e. Groth et al. in prep).
An electronic database was initiated and developed by PWS to accommodate a range of information relating to nesting birds and attributes of nesting habitat. A selection of fields from the database were incorporated into the PWS GIS and are available for use in land and management planning processes. These data also provide the basis for assessment of breeding success, habitat monitoring and analysis, and predictive modelling. Maintenance of the database is ongoing and information is updated as breeding data are received, additional nests are located and on-ground habitat surveys are undertaken.
The aim of public relations has been to increase awareness of the plight of A. a. fleayi and reduce persecution. Talks and displays have been presented to the general public and a range of interest groups and professional organisations, including Landcare, schools and rural groups. Numerous articles have been published in local newspapers or on local and national radio, and local and national television.
A brochure titled 'Eagles on the Farm' was prepared and distributed to over 14 000 properties throughout rural Tasmania. It summarises the biology of the species, offers guidelines for management of nesting habitat, advice for landowners in relation to predation of sheep and highlights the benefit to farms of protecting eagles. Response to the brochure from landowners has been enthusiastic.
A combination of aerial and ground based surveys (conducted in 1989, 1992, 1993, 1994 and 1997) were used to assess the breeding success of the subspecies. These data were combined with similar data collected by PWS between 1983 and 1989 and were used to identify the overall trend, and disparities in breeding success between 'disturbed' and 'undisturbed' nests.
1.9 Strategy for Recovery
A. a. fleayi is endemic to Tasmania with a naturally small population. Survey data has clearly shown the breeding success of a high proportion of the adult population is declining (Mooney in prep.) as a result of destruction and disturbance of nesting habitat. The factors contributing to this decline can be ameliorated. Furthermore, there is considerable evidence of a high level of unnatural mortality from persecution and accidental deaths. These can also be ameliorated. Although there are no rigorous estimates of abundance (nor are there for others of the genus), the magnitude of decline in breeding success coupled with high unnatural mortality may have caused a downward trend in the size of the mature population (evidence of this is the high proportion of unsuccessful territories, territories with none or only one adult and the high replacement times for adults lost to territories) and a threat to the long term viability of the subspecies.
The previous recovery plan set out with the objective to downlist the conservation status of A. a. fleayi from endangered to vulnerable. Specific objectives were to increase breeding success by reducing disturbances and destruction of nesting habitat and increase public awareness to reduce persecution. Several actions were implemented in the previous plan. Nest sites were surveyed, interpretive and educational material was prepared and disseminated, a GIS database was established and maintained, the genetic variability of the subspecies was investigated and prescriptions for protection of nesting habitat were further developed and incorporated in the management of production forest. The objectives of the new plan are consistent with, and extend those of the previous plan. Some of the previous actions will be ongoing and new actions have been identified in the light of a better knowledge of the subspecies' conservation requirements, recent research findings, and a need to better quantify progress towards the objectives.
The new plan focuses on the eagle's nesting habitat and two approaches are taken to stem the decline in the species' breeding success.
- Firstly, nests in undisturbed forest habitat will be found ahead of forestry and other land development to ensure appropriate reservation and management prescriptions are applied. A considerable amount of on-ground survey will be necessary to ensure nests are found prior to forestry clearing operations and this action will not be possible without a considerable volunteer contribution from the Australasian Raptor Association.
- Secondly, disturbed nests, and those under potential threat on private land will be targeted for land management agreements with owners/mangers.
Hence, undisturbed nests will not be unintentionally destroyed or fall into a higher category of disturbance, with consequent reduction in their breeding success and by appropriate management and long term security of eagle nests on private land, a contribution will be made towards improving the overall breeding success of the subspecies.
An increase in the breeding success may not be sufficient, on its own, to increase the total adult population while the rate of persecution and other human induced mortality remains high. Therefore, a program of education and information will continue with the aim of reducing the level of these parameters.
Population monitoring will provide the basis for determining the success of major actions, and a significant improvement in breeding success i.e. the number of nests fledging young, will need to be demonstrated for success in achieving the plan's principle objective.
2 RECOVERY OBJECTIVES AND CRITERIA
The overall objective is to achieve down-listing of A. a. fleayi from endangered to vulnerable within five years of the implementation of this plan by maintenance of the population and reduction of threats.
|Specific Objectives||Criteria for Success||Actions|
|Reduce the incidence of disturbance of eagle nests through adequate planning for proposed forestry and land clearing operations at a strategic level.
|Û Increased proportion of new nests identified in undisturbed old growth forest on private land and State Forest before forestry and land clearing operations.
Û Increase in the number of nests found in production forest that are active the following year.
|Develop further predictive models of nesting habitat for regional application.
Produce maps identifying high probability nesting habitat on State Forest and private land.
Search for nests in high probability nesting habitat on State Forest and private land.
Trap, radio-tag and track resident adults to find their nests.
Provide advice to FT, PFC and private land owners on the location and conservation of nests before forestry and land clearing operations.
|Reduce the incidence of disturbance of eagle nests by adequate planning of proposed forestry operations at the Forest Practices Plan level.||Û Increased proportion of new nests identified in proposed forestry coupes prior to forestry operations.||
|Conduct pre-logging surveys within proposed forestry coupes.
Provide advice to FT, PFC and private land owners on conserving nesting habitat in proposed forestry coupes before forestry operations.
|Protect nesting habitat on private land.||Û Thirty agreements with private land owners for long term security of nesting habitat.||
|Assess voluntary agreement options for conserving nesting habitat on private land.
Establish agreements with individual land owners.
Assess security of eagle nest reserves.
|Protect nesting habitat on State Forest.||Û Long term protection of prescriptive reserves for nesting habitat on State Forest.||
|Ensure nests are reserved from logging and prescriptions applied.
Assess security of eagle nest reserves.
|Monitor breeding success and abundance.||
Û Identify trends in breeding success and refine prescriptions for conserving nesting habitat.
Maintain a nest site register.
Survey breeding success at selected nests.
Assess abundance (road counts).
Update management prescriptions for nesting habitat.
|Reduce the incidence of human induced mortality.||
Promote conservation of eagles to land owners/managers.
Monitor reports of natural mortality and human induced mortality such as persecution, accidental poisoning, collisions and electrocution.
Monitor reports of natural mortality and human induced mortality such as persecution, accidental poisoning, collisions and electrocution.
3 RECOVERY ACTIONS
Costs of recovery actions are based on 1997 prices. Costs of a scientific officer (SO1) are based on a salary of $37 100 with add-on costs of 28%; technical officer on a salary of $27 917 with add-on costs of 28%; vehicle hire at $1 000 per month and travel allowance at $25 per day.
3.1 Find Nests on Private Land and State Forest
Rationale: Forestry operations on State Forest and private land in the past have occasionally led to the destruction of nest trees or, more commonly, the desertion of nests caused by logging and/or road construction. Most nests are found at a stage during logging where it is too late to provide ideal protection for the site. Nest searches in advance of forestry and other forest clearing activities are therefore essential if adequate protective measures for nest sites are to be implemented. A knowledge of the location of nests will enable better planning of forest harvesting operations, greater scope for the implementation of nest site prescriptions, reduce unintentional disturbance and destruction of nests and reduce the need for nest site 'rescues'. This action will use predictive models and telemetry to find nests at a strategic level, well in advance of logging activities, and use predictive models and existing search techniques to locate nests, at the forestry coupe level.
3.1.1 Develop Predictive Models of Nesting Habitat
Description: A predictive model of nesting habitat with application to eastern Tasmania (developed during the Tasmanian RFA process) will be further refined and modified for use in other regions. Predictive models are expected to be necessary for a further 6 regions including the north, north-east, north-west, west, south and central highlands. These models will be used to prioritise areas of State Forest and private land for nest searches. A scientific officer (for 3 months full time each year for 3 years) will be required to further develop and modify models using GIS data held by PWS and FT. Following validation procedures, maps identifying areas of high probability nesting habitat will be produced. The maps will guide implementation of Actions 1.2, 1.3 and 1.4.
Funds are required to employ a scientific officer, for use of PWS and FT GIS facilities and expertise, and for the production of maps.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|19400||19 400||19 400||58 200|
3.1.2 Search Prioritised Forest Areas for Nests
Description: Extensive ground searches for nests will be required to validate regional models, identify alternate nests in territories where previously active nests have been abandoned and identify additional nests in undisturbed habitat. The search radius for alternate nests will be based on local site characteristics and known patterns of alternate nest selection. As maps of predicted high probability nesting habitat are completed they will be used to guide requirements for pre-logging nest searches (1.4). A technical officer will be required (full time for 3 months per year over 3 years) to conduct on-ground nest searches. Volunteers will be required to assist in searching at all times.
Funds are required to employ a technical officer, for travel allowance and vehicle hire. Costs of volunteers time is included.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|39 000||39 000||39 00||117 000|
3.1.3 Trap, Radio-Tag and Track Resident Breeding Birds to Their Nests
Description: In areas where predictive modelling is indiscriminant or where high probability nesting habitat is logistically unsuitable for ground searching, telemetry will be used to locate active nests. Adult birds will be trapped, then radio-tagged and tracked to their nests. A technical officer (full-time for 2 months in year 1 and 1 month during year 2 and year 3) will be required to develop trapping and telemetry techniques and to undertake radio-tracking during the breeding season.
Funds are required to employ a technical officer, for travel allowance, vehicle hire and telemetry equipment. Costs of volunteers time is included. The number of nests located in year 1 will provide the criterion for review of the task's success and ongoing funding in year 2 and year 3.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|19600||9 800||9 800||39 200|
3.1.4 Search for Nests in Proposed Logging Coupes
Description: During the period of the recovery plan it will be necessary to continue pre-logging nest searches on State Forest and private land in response to the FPP process. In 1996, nest searches were conducted in about 50 logging coupes by PWS, FT and PFC. Following year 3 of the plan a standardised process should be in place (based on maps of high probability nesting habitat) to assess specific requirements for on-ground nest searches. As additional areas of high probability nesting habitat are searched and additional nests are located, the requirement for pre-logging nest searches will diminish. PWS will undertake coupe priority assessment, provide expert advice and training of personnel and/or contractors in pre-logging nest searches.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|19400||19 400||19 400||19 400||19 400||97 000|
Rationale: Protection of nests on private land and State Forest is essential to the long term survival of A. a. fleayi. Under the Forest Practices Code, nests are reserved and management prescriptions applied during forestry operations; on State Forest nests are reserved in Wildlife Protection Areas or incorporated in other reserves, while on private land the fate of prescribed reserves relies on the goodwill of the land owner. Little protection is afforded nesting habitat on private land that is not covered by the Forest Practices Code and cleared for other purposes. This action will assess the long term viability of eagle nest reserves on private land and State Forest and will target the long term conservation of nests on private land by development of land management agreements, with voluntary participation by landowners.
3.2.1 Protect Nesting Habitat on Private Land
Description:This action will involve the identification and implementation of long term conservation measures for nesting habitat on private land. A scientific officer will be required (full time for 3 months each year for 3 years) to prioritise, by conservation need, known nests on private land and liaise with private land owners. Long term conservation of nests will be the aim of liaison and the preparation of land management plans will be an important step in the agreement process. Land management plans will define the area of land affected, specify objectives for management, and specify actions to be undertaken by the PWS and/or the private land owner(s) to conserve nesting habitat.
Funds are required to employ a scientific officer, for travel allowance, and vehicle hire.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|14 420||14 400||14 400||43 200|
3.2.2 Assess Security of Eagle Nest Reserves
Description: Data and observations on the status of eagle nest reserves will be collected by direct field survey and by consultation with private and State Forest land managers. All existing and newly prescribed eagle nest reserves will be assessed in the first year and again in the final year of the plan. A protocol will be prepared to assist field officers in the assessment of the integrity of the reserve and ensure a basis for quantitative analysis. A scientific officer will be required for 1½ months to undertake field survey, consult with land owners and forest industry officers and report on the long term viability of eagle nest reserves.
Funds are required to employ a scientific officer.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|7 000||7 000||14 000|
3.3 Monitor Breeding Success and Abundance
Rationale: The results of the survey of breeding success will be used to measure progress in achieving recovery objectives. Ultimately, success in reaching the principle objective will be indicated by a reduction in the disparity of breeding success between 'undisturbed' and 'disturbed' nests. Although estimates of absolute abundance are more problematic to achieve, data indices of abundance and adult: juvenile ratios from road counts and incidental reporting can be used in combination with more rigorous survey results of breeding success to determine the overall trend in population size.
3.3.1 Maintain Nest Site Register
Description: An electronic database was initiated and maintained as part of the previous recovery plan. Information held on the database was used to update the PWS GIS and FT GIS. This database will continue to be maintained and updated during the period of the current plan. Selected fields will be entered into the newly established 'Threatened Species Database' which allows for regular updating of the PWS GIS. The database will be used in prioritising the requirements for land management agreements and preparation of land management plans, and will be available to researchers, field workers and the forest industry for conservation management and planning purposes. The database will also house information collected by other actions such as 1.2 - 1.4, 2.2, 3.2 and 3.3. A technical officer will be required to manage and update the nest site register.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|3 600||1 800||1 800||1 800||1 800||10 800|
3.3.2 Survey Breeding Success
Description: The breeding success at a selection of nests ('undisturbed' and 'disturbed'), on private land, State Forest and formal reserves will be surveyed every second year of the plan (i.e. year 1, 3 and 5). A combination of aerial, using fixed-wing light aircraft, and ground based surveys will be used to examine the contents of nests in late nestling stage (mid-November to mid-December). Natural mortality is extremely low in the second half of nestling life so nests containing chicks with at least some feathering can be regarded as successful. In addition to recently discovered nests, those with a known breeding history (i.e. nests surveyed prior to and during the previous plan) will be included in the survey sample. To detect differences in the breeding success of nests among land management regimes, and trends over time, a large number of nests will be surveyed. A technical officer will be required (one month full time in year 1, 3 and 5 of the plan) to assist with aerial survey and associated on-ground survey.
Funds are required to employ a technical officer for one month full time and for aircraft charter.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|14 500||14 500||14 500||43 500|
3.3.3 Assess Abundance
Description: Throughout field work, over the duration of the plan, road counts will be carried out (as for the Birds Australia BOP Watch program) and eagles scored as adult or juvenile.
3.3.4 Update Management Prescriptions for Nesting Habitat
Description: Information and data collected by actions 2.2 and 3.2 and other incidental information will be used to reassess the adequacy of existing management prescriptions. If necessary, a refined set of recommendations for conserving nests will be prepared.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|2 500||2 500|
3.3.5 Monitor Reports of Mortality
Description: The incidence of natural and human induced mortality (including persecution, accidental poisoning, collisions and electrocution) will be monitored. PWS are often advised of eagle mortality by interested and concerned members of the public and by veterinarians or officers of other government authorities. Tasmania's museums also receive carcases, often road killed animals. Wherever possible, carcases will be examined to determine the cause of death, age and sex. Individuals will be allocated to categories of cause of death and an assessment made annually of the total number and proportion of birds within each category. These data will be used to determine trends in causes of mortality.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|1 500||1 500||1 500||1 500||1 500||7 500|
3.4 Promote Eagle Conservation to Land Owners and Managers
Rationale: Public information and education has the potential to reduce the rate of persecution of eagles, and to some extent, other human induced mortality such as collisions with vehicles. Although changing attitudes to eagle conservation are apparent within the community the degree of change and/or the size of any reduction in the level of persecution is difficult to quantify. Nonetheless, some impression of the success of reducing persecution and other human induced mortality may be indicated by trends in the causes of mortality (i.e. proportions of eagles dying from natural causes verses those dying from human induced causes; action 3.6). It is also important that education and information on the conservation of eagles (including both the costs and benefits) reaches the intended audience i.e. rural landowners and managers, and the forest industry. The 'Eagles on the Farm' brochure was produced during the previous plan and distributed to over 14 000 properties. It received a positive response from the media and private land owners, however, many rural properties did not receive the brochure.
Description: The 'Eagles on the farm' brochure will be reprinted and distributed to additional landowners. PWS will also make the brochure available to other interested persons. The Parks and Wildlife WWW pages of the DELM Home Page provide information on threatened species and their conservation management. Current information on the eagle will be expanded to include comprehensive details on the conservation of eagle nests. Regular review of the content will enable land owners/managers using the internet to access updated information.
Eagle conservation will continue to be promoted through its inclusion in training of Forest Protection Officers (currently conducted 3-4 times per year by PWS officers) and will be extended to other training and academic courses such as Chainsaw Safety Training, Town Planning at the University of Tasmania and other relevant courses. To assist land owners and the forest industry, a training video on eagle nest protection procedures and prescriptions will be prepared.
The public profile of A. a. fleayi and its threatened status will be maintained by continuation of general public lectures and presentations, and opportunistically through articles in the print and electronic media.
Funds are required for reprinting and distribution of the 'Eagles on the Farm' brochure and for the preparation of a training video on eagle nest conservation.
|Yr 1||Yr 2||Yr 3||Yr 4||Yr 5||Total|
|7 000||9 000||4 000||9 000||4 000||33 000|
3.5 Continuity and Supervision
PWS will provide continuity of supervision of this program. PWS is the major data repository and it is expected that Nick Mooney of the Nature Conservation Branch will be involved in each of the specific actions.
4 IMPLEMENTATION SCHEDULE
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|Task No.||Task Description||Priority||Feasibility||Responsible Party||Cost Estimate ($000s/yr)|
|Year 1||Year 2||Year 3||Year 4||Year 5||Total|
|1||Identify nest sites on private land and State Forest|
|1.1||Develop predictive models of nesting habitat||2||100%||PWS||19.4||19.4||19.4||58.2|
|1.2||Search prioritised forest areas for nests||2||100%||PWS||39.0||39.0||39.0||117.0|
|1.3||Trap, radio-tag and track resident breeding birds to their nest sites||2||80%||PWS||19.6||9.8||9.8||39.2|
|1.4||Search for nests in proposed logging coupes||2||100%||FT/PFC/PWS||19.4||19.4||19.4||19.4||19.4||97.0|
|2||Protect nesting habitat on State Forest and private land|
|2.1||Protect nesting habitat on private land||1||80%||PWS||14.4||14.4||14.4||43.2|
|2.2||Assess security of eagle nest reserves||1||100%||PWS||7.0||7.0||14.0|
|3||Monitor breeding success and abundance||.|
|3.1||Maintain a nest site register||3||100%||PWS||3.6||1.8||1.8||1.8||1.8||10.8|
|3.2||Survey breeding success||3||100%||PWS||
|3.4||Update management prescriptions for nesting habitat||3||100%||PWS||2.5||2.5|
|3.5||Monitor reports of mortality||3||80%||PWS||1.5||1.5||1.5||1.5||1.5||7.5|
|4||Promote eagle conservation to land owners/managers||2||100%||PWS||7.0||9.0||4.0||9.0||4.0||33.0|
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Front cover illustration by Karen Richards.
Endangered Species Program Project Number 578. Funded by the Endangered Species Program, a program of the Natural Heritage Trust. The views expressed in this document are those of the authors.
Cite as: Bell, P. J. & Mooney, N. J. (1998) Wedge-tailed Eagle Recovery Plan 1998-2003. Department of Primary Industries, Water and Environment, Hobart.
Copyright © The Director, Parks and Wildlife Service, Department of Primary Industries, Water and Environment, GPO Box 44A, Hobart, Tasmania 7001.
Apart from fair dealing for the purposes of private study, research, criticism or review as permitted under the Copyright Act, no part may be reproduced by any means without the permission of the Director, Parks and Wildlife Service.