Application for Scientific Permit – Available for Public Comment
Applicant: University of Tasmania
Species/Taxon: Tasmanian wedge-tailed eagle (Aquila audax fleayi)
Location: State Forests, crown land, privately owned land and PWS reserves throughout Tasmania. The location of field work is dependent on the location of trapping attempts and where the eagles go after the GPS transmitter is attached (i.e. if the GPS data from a tracked eagle indicates that the research team needs to carry out a field visit or recapture attempt). Adult eagles are less likely to travel large distances than immatures, however, adults have the ability to travel anywhere in the state.
Title of research: Investigating the flight behaviour and conservation requirements of adult Tasmanian wedge-tailed eagles (Aquila audax fleayi)
Aim of project: To use high-frequency GPS tracking technology to understand Tasmanian wedge-tailed eagle flight behaviour and to identify high-risk areas for powerline and wind turbine placement. The project has five specific aims:
- Develop state-wide models of eagle collision risk
- Ascertain the habitat requirements of adult Tasmanian wedge-tailed eagles
- Quantitatively estimate the territorial capacity of Tasmania
- Obtain data on the causes and rates of adult mortality across the population
- Clarify the rates of exposure to environmental contaminants in the Tasmanian wedge-tailed eagle population
- Test for evidence of disturbance caused by forestry operations that occur within LOS and between 500m – 1km of active eagle nests
Justification: The Tasmanian wedge-tailed eagle is listed as endangered at both a state and federal level. Despite their endangered status, there is very little known about the behavioural ecology of the subspecies. This poor understanding necessitates a better insight into its ecology to guide conservation efforts. GPS tracking technology has greatly increased resolution in recent years, with the potential to provide a much better understanding of behaviour. These very detailed behavioural observations can be used to inform the conservation management of threatened species.
The Tasmanian wedge-tailed eagle is vulnerable to collisions from wind-turbines and powerlines. With increasing energy infrastructure planned for Tasmania there is a need for tools to reduce this conflict. In the United States, GPS tracking has been used to develop models that identify high and low risk locations for energy infrastructure. A similar model for Tasmania will provide an impact assessment tool that can guide the positioning of energy infrastructure at a regional scale and the mitigation and siting of individual assets at a local scale.
The Tasmanian wedge-tailed eagle is highly sensitive to disturbance during the breeding season. Management recommendations designed to reduce the impacts of disturbance define that human activities are restricted within 500 m/1 km line-of-sight (LOS) of nests with breeding eagles. With a large number of the known eagle nests occurring on forestry land, these recommendations are particularly focused towards the forestry industry (but are also used to manage a multitude of other residential, recreational and industrial activities). Studies have not found any evidence of adverse impacts from forestry if conducted under the current recommendations, but all of these studies have had limitations to the strength of the conclusions that can be drawn (if any could be drawn given the methods used). Due to the potential impacts on the Tasmanian wedge-tailed eagle population, it is important that we collect quantitative data on the effectiveness of current management recommendations. GPS-tracking technology allows for very detailed behavioural observations that can be used to measure disturbance impacts.
Maximum likely numbers of individuals involved: The project aims to attach GPS transmitters to 50 adult Tasmanian wedge-tailed eagles. This sample size has been decided upon to provide enough information to address each of the project aims.
Activities undertaken and methods: The methods used in this study have been carried out successfully over the last four years on one adult and 25 immature Tasmanian wedge-tailed eagles under permits TFA18251 and TFA17328. This project aims to apply these methods to study 50 adult Tasmanian wedge-tailed eagles.
Established techniques will be used to capture the eagles (modified crow trap, dho gaza, bal chatri, net launcher and bow net). All trapping will be supervised by members of the research team highly experienced in raptor trapping, handling and GPS transmitter attachment. When active, all traps will be under constant monitoring to increase the likelihood of capturing target eagles and reduce the likelihood of the capture of non-target species (e.g. forest ravens).
Upon capture the eagle will be carefully restrained using appropriate techniques. At least two members of the research team will be present for all trapping so that one member can hold the eagle whilst the other member can carry out a detailed check of the bird, collect a ~2 ml blood sample and fit the GPS transmitter. The blood sample will be used for genetic and contaminant analyses. All blood samples will be collected by personnel competency assessed for this procedure. The UTAS ethics vet will be contacted if a captured bird is in poor condition (e.g. body condition <2, high parasite load, has any injuries or evidence of poisoning).
The GPS units collect data on the location, altitude, direction, speed and activity level every 6 seconds - 15 minutes. This data is sent via the mobile phone data network to the research team. The research team will monitor this data every 1-2 days for any potential welfare concerns (e.g. changes in activity levels) that may be indicative of injury or poisoning. The data will also be monitored to check the correct functioning of the GPS units (i.e. solar battery charge levels).
If the data suggests a welfare or technological issue, the eagles will be assessed in the field through visual observation to check for any difficulty in flying, abnormal behaviour or feathers covering the solar panel of the GPS unit. In the event of a bird requiring recapture, the same capture techniques listed above will be used, and the bird will be examined by a raptor specialist.
If the GPS data suggests a mortality a field check will be carried out. In the event that a tracked eagle has died the carcass will be retrieved and the UTAS ethics vet contacted. A post-mortem will be carried out to attempt to identify the cause of death. The standard protocol will include analysing a liver sample for sources of poisoning (e.g. lead and rodenticides).
This project will include an experimental design utilising the GPS data to specifically test for evidence of disturbance caused by forestry operations that occur within LOS and between 500 m – 1 km of an active eagle nest. A forestry operation will be introduced between 500 m – 1 km LOS of nest sites used by 12-20 of the GPS-tracked eagles. We plan for the operation to be harvesting, but sites will include
opportunities for log carting if harvesting is not possible. The operation will be carried out during the incubation phase of the breeding season. Information on the days/times, specific location, and description of the operation (e.g. number of people, vehicles, machinery) will be recorded. The analytical approach will test for disturbance by measuring:
- Fine-scale behavioural change at experimental nest sites during days/times of forestry operations
- Differences in behaviour between experimental (forestry operation introduced between 500 m – 1 km LOS) and control nest sites (standard management applied)
Fate of animals: All captured eagles will be released at the site of capture unless veterinary treatment is required due to poor condition or evidence of lead or rodenticide poisoning. Trapping attempts will be made to remove GPS transmitters when they show signs of reaching the end of their lifespan (expected to be in > 3-5 years). The transmitters used have been applied to various endangered raptor species throughout the world (including Tasmanian wedge-tailed eagles) and there are not expected to be long-term welfare impacts from carrying the transmitters.
Likely impact on species involved (including any by-catch): The eagles will experience some stress by the capture and handling. However, the refinement of raptor research techniques has helped minimise stress. There is a chance that non-target bird species will be caught (e.g. forest ravens). In such cases, it is not expected that any harm will be caused, and the research team will immediately release any caught individuals. Although stress may be caused by the introduced forestry activity, the behavioural measures of this stress will be important in reviewing/justifying current regulations.