Masked owl - Tyto novaehollandiae (castanops)
Application for Scientific Permit – Available for Public Comment
Public comment on the following application for a Scientific Research (Fauna) Permit is open until 12 March 2020.
Applicant: Forest Practices Authority
Species/Taxon: Tyto novaehollandiae (castanops)
Location: State Forests, privately owned land (Southern Tasmania). The location of field work is dependent on where owls are located following call playback surveys.
Title of research: The spatial ecology of masked owls (Tyto novaehollandae castanops)
Aim of project: To investigate the ecology and habitat requirements of masked owls we will:
- Determine the attributes of roost and nest sites
- Identify home range size and habitat utilisation patterns within the home range
- Explore the landscape and habitat associations of roost and nest site localities, in particular the association with spatial layers used to currently manage the species (ie determine if we map where they are likely to roost/nest).
Justification: Hollow-using species require careful management in production forests, due to the reduction in hollow-availability that occurs in a forestry landscape. Masked owls are one of the largest hollow-using species in Tasmania, but we know very little about their ecology. Current management of this species in the forestry context focuses on a landscape approach, whereby harvesting may occur as long as specified thresholds of maturity are available in the broader landscape, as assessed from the FPAs ‘mature habitat availability map’. However it has not yet been tested how well this map reflects areas used by masked owls or the effectiveness of the management approach. The current project seeks to learn more about the hollows, trees and sites that masked owls use for roosting/nesting so that we can assess whether this landscape approach to managing masked owls is effective, or if more localised measures are warranted. The results of this research will help improve conservation measures for this species.
Maximum likely numbers of individuals involved: Only a small number of birds are being proposed for the current study (7-10). This is the smallest number of birds we could use that would still allow us to make inferences on the character of their roost sites. As multiple roost sites are typical per bird, the effective sample size will be >20 which will be adequate for statistical analysis.
Activities undertaken and methods: A harness and GPS tracking device will be attached to each bird for between 1 and 3 months.
Owls will only be trapped in a Dho-gaza net by personal who have significant experienced in trapping, handling and GPS transmitter attachment, including of masked owls.
Upon capture, owls will be carefully restrained and a detailed assessment of the owl’s condition will be done. If the birds are in good condition they will be fitted with a standard Australian Bird and Bat Banding Scheme band, a harness with a weak link system and a GPS transmitter. If there are any concerns about the condition of the bird the UTAS ethics vet will be contacted.
The harness is made of a Teflon ribbon, where four straps are joined together on the keel of the bird by a single strand of cotton thread. This single stitch is a weak link that will break after approximately 3 months and can be broken by the bird in the unlikely event that the harness gets caught on something. The design used ensures all parts of the harness are released simultaneously so the owl will not become entangled when the harness is shed.
The GPS units collect data on the location, altitude, direction and speed of the bird approximately 9 times a day. The units will be programmed to target the busiest activity period (as determined from a pilot study involving a single bird), as well as just before dawn and after dusk. The data are sent via radio link to a receiver that will be deployed within the owl’s territory. The research team will initially monitor these data every day for the first few days, then every 3 or so days to monitor the welfare of the birds (e.g. unexpected activity levels).
The transmitters used in this work have a pinger function (which acts like a normal VHF transmitter) that allows researchers to work out the direction and distance of the owl if the individual needs to be located. The data downloaded and the pinger function will be used to locate the roost sites of the birds. Cameras will be established at approximately 15 roost sites to monitor use of the roost over a period of months.
The GPS units will last for approximately one month, after which the battery runs out. The pinger will run for a number of weeks beyond this time to help locate the birds for re-trapping.
If there is any concern about a welfare issue or when the GPS transmitter has run out of battery, attempts will be made to re-trap the birds using the same method as the initial trapping (the Dho-gaza trap).
Fate of animals: Upon recapture the condition of the animals will be reassessed and compared to that before attachment of the harness and transmitter. The birds will then be released, except in the unlikely event that there is a welfare issue in which case the university ethics committee vet will be contacted.
Likely impact on species involved (including any by-catch): Owls will experience some stress from capture and handling. However, the techniques used and the experience of the researchers means the stress is expected to be a little as possible and only brief. There are expected to be no long-term impacts on the individuals involved in the study.
Non-target species are unlikely to be caught, with the only possible species being bats or other nocturnal birds. If captured the research team will immediately release them after a quick assessment to ensure they are not harmed. The team have extensive experience to undertake basic assessments of animal welfare.