Tasmanian masked owl (Tyto novaehollandiae castanops)

​​Application for Scientific Permit – Available for Public Comment

Public comment on the following applicaiton for a Scientific Research Permit (Fauna) is open until 23 July 2024

Applicant: University of Tasmania

Species/Taxon: Tasmanian masked owl (Tyto novaehollandiae castanops)

Location: State Forests, crown land, privately owned land, and PWS reserves throughout Tasmania. The location of fieldwork is dependent on the locations of trapping attempts that are currently unknown, and where the owls go after tracking tags are attached. In the event an owl becomes injured while being tracked, researchers will need to access its location to check the welfare of the bird. After approximately two weeks of tracking, researchers will also need to access owl locations to remove their tracking units. Tasmanian masked owl (TMO) habitat can be found statewide, and their movement behaviour is largely unknown. For these reasons, access to a variety of land tenures across the state is required. Permission will always be sought from private landowners before accessing their properties.

Title of research: Conservation ecology of the Tasmanian masked owl (T. n. castanops): bioacoustics, habitat selection, and rodenticide toxicology  

Aim of project: This project will help provide the knowledge needed to maintain TMOs as a key element of biodiversity in the landscape. The concerning conservation status of TMOs requires advancements in our understanding of several aspects of their ecology. This project seeks to fit 25-40 TMOs with acoustic+GPS tags to address four aims:

1) Improve passive acoustic monitoring (PAM) methodology for better TMO surveying.
2) Investigate habitat selection involved with different owl behaviours.
3) Examine the prevalence and severity of anticoagulant rodenticide exposure in the TMO population.
4) Synthesize findings of Aims 2 & 3 with nest camera data to generate an improved population viability analysis.

Justification: The Tasmanian masked owl is listed as endangered at the state level, and vulnerable at federal level. Despite their endangered status, the requirements of these birds are poorly understood beyond studies of distribution at large spatial scales and speculative claims informed by small sample sizes. This lack of information necessitates new research to guide improved 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. Here, we propose using acoustic+GPS tags that also collect on-owl audio data. Analysis of acoustic data will provide valuable information about the calling behaviour of TMOs, which will improve our ability to locate and protect them. Lastly, this research will also investigate the threat of anticoagulant rodenticide to these birds, which may be a serious concern for many Tasmanian species.

Maximum likely numbers of individuals involved: Tasmanian masked owls (Tyto novaehollandiae castanops): 
This project proposes the tracking of 25-40 individuals.

Activities undertaken and methods: The trapping methods used in this study have been carried out successfully on six Tasmanian masked owls (T. n. castanops) under a previous Scientific Permit and Animal Ethics Committee Approval. This project seeks to investigate new aspects of masked owl ecology with the aim of reaching 25-40 GPS-tracked and acoustically monitored Tasmanian masked owls.  

Established techniques will be used to capture the owls (modified dho-gaza, bow net, or noose carpet). All trapping will be supervised by members of the research team highly experienced in raptor trapping, handling, and GPS tracker attachment. When active, all traps will be under constant monitoring to increase the likelihood of capturing target owls and reduce the likelihood of capturing non-target species (e.g. bats). 

Upon capture the owl 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 owl whilst the other member carries out a detailed check of the bird, collects a ≤2 ml blood sample, assesses plumage characteristics, attaches a bird band (banders will hold ABBBS licenses), and fits an acoustic+GPS tag. The blood sample will be used for genetic and rodenticide 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 Acoustic+GPS tags simultaneously collect GPS data on the location and altitude of birds every 10 seconds – 1 minute, and record on-owl audio recordings. To monitor birds while they are being tracked, these units also contain a VHF radio transmitter. The research team will monitor owls with the VHF radio tracking for any potential welfare concerns (e.g. changes in activity levels or lack of movement) that may be indicative of in​jury or poisoning. 

If the movement (or lack thereof, as indicated by VHF radio tracking) of owls suggests a welfare issue, the bird will be assessed in the field through visual observation to check for any difficulty in flying or abnormal behaviour. 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. To collect the acoustic+GPS data, birds will need to be re-trapped after 1-3 weeks of tracking to permanently remove the tags.

If the VHF tracking suggests a mortality, a field check will be carried out. In the event that a tracked owl 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.

In addition to tracking, owls will also be monitored with stationary microphones using a technique called passive acoustic monitoring (PAM). PAM involves placing audio recorders in an owl’s home range, which collect acoustic data throughout the night. These data can be analysed to determine an owl presence near a recorder. The passive nature of this technique means that these devices will not directly interact with owls in any manner but will collect audio recordings of the surrounding area. PAM has been used on Tasmanian masked owls in a previous project.

Lastly, this project also seeks to investigate the nesting and roosting behaviours of these birds. The tracking data from individuals may reveal where they are nesting and roosting. To research behaviours at these locations, passive infrared cameras will be installed outside of utilized tree hollows. Installation will only occur when owls are not present. These methods have been used on Tasmanian masked owls in a previous study, and do not require any additional capture or handling of the birds.

Fate of animals: All captured owls will be released at the site of capture unless veterinary treatment is required due to poor condition or evidence of rodenticide poisoning. Trapping attempts will be made to remove the acoustic+GPS tag after 1-3 week of tracking. The tags used have been applied to bats and another endangered owl species (Strix occidentalis), and no long-term welfare impacts are expected from carrying these devices. 

Likely impact on species involved (including any by-catch): The owls 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 and bat species will be caught. In such cases, it is not expected that any harm will be caused, and the research team will immediately release any caught individuals. 


Scientific Research Permits

Environment Division
GPO Box 44,
Hobart, TAS, 7000.