Feral cat (Felis catus)

​Application for Scientific Permit – Available for Public Comment 

Public comment on the following application for a Scientific Research (Fauna) Permit is open until 9 June ​

Applicant: University of Tasmania

Species/Taxon: Feral cat (Felis catus) 

Location: South-east of Tasmania (conservation area, permanent timber production zone land, game reserve). 

Title of research: Optimizin​g camera-trap use for feral cat monitoring- strategic versus systematic camera placement and the role of lures.

Aim of project: Feral cats are a threat to native wildlife and are difficult to monitor. Camera traps appear to be one of the few accurate, non-invasive methods (i.e., not requiring the capture or handling of the animal) for measuring their occupancy and abundance. However, we have not yet optimized methods for camera trap placement to maximise their efficiency and increase cat detection rates. Most camera-trap studies opt to place cameras in a grid layout, with cameras separated by the target species’ average home-range size. This is thought to ensure an "unbiased" design, but some scientists have speculated that this layout is inefficient, and that a better approach is to use fewer camera traps but place them in strategic locations where cats are known to frequent, such as roads, trails, and good hunting grounds.

Furthermore, these cameras are generally baited, either with visual, olfactory, or food lures. Lures are used to maximise detection rates of feral cats in short-term camera trap studies and to encourage cats to stay at the camera trap to provide more images for individual identification. However, previous in-field experiments have found no increase in detection rates between baited and unbaited camera traps and that cats display little response to lures and baits. Despite this, baits have been deployed in all previous camera-trap studies targeting feral cats within Tasmania. These studies have favoured food baits and olfactory lures, the redeployment of which has limited the time cameras can be left undisturbed in the environment (e.g. unbaited cameras can be left for five-six months when using lithium batteries, but baited cameras must be visited at least every 20 days by a researcher to replenish the lures). 

A recurring question is whether we can increase the detection rates of feral cats by placing cameras in positions more likely to capture cats, such as on trails and roads, or by baiting camera traps with lures. As such, I aim to compare systematic (grid-like) placement and strategic camera placement, as well as baited vs unbaited cameras, with the goal of maximising the efficiency of future feral-cat surveys using camera traps. Improving these methods will increase our understanding of feral cat ecology within forested environments so that we can better manage this invasive species. 

Justification: This project will identify how useful lures are for increasing feral cat detection rates. Considering past research, the hypothesis is that lures will not increase feral cat detection rates as compared to well-positioned unbaited cameras. Quantifying the impact (or lack thereof) of lures on camera trap detection rates could reduce the use of baits in future studies, lowering the impact of future camera-trap studies on native species, increasing the efficiency of feral species monitoring efforts, and therefore lowering costs associated with feral species management.

Using baits could disrupt regular activity patterns of quolls, Tasmanian devil, and feral cats, but are unlikely to impact other wildlife. Some animals may avoid the baited area, disrupting their normal foraging patterns. Placement of camera traps might result in fine-scale habitat disturbance. The trade-off is that we gain a greater understanding of feral-cat distributions, activity, density, and monitoring strategies that can inform future management efforts, in a shorter time period and with fewer cameras. One of the greatest pitfalls to feral-cat control is a lack of appropriate monitoring methods (Nichols et al., 2019). This study will address that knowledge gap and increase our capacity to monitor and manage feral cats, potentially improving future control methods for feral cats and protecting native species.

Maximum likely numbers of individuals involved: Up to 4000 animals images are likely to be taken by the camera traps across the study based on previous monitoring efforts. 

Activities undertaken and methods: No animals are obtained/captured within the experiment. UTAS animal ethics approval has been granted for the following methods (UTAS ethics number: A0023747) 

For aim 1. To compare the detection rates and abundance estimates of systematically placed grid-layout camera traps with strategically placed cameras along trails and roads in forested sites: 
Remotely triggered camera traps will be deployed simultaneously (within the same week) in 4 × 4 grids (a total of 16 cameras per grid), with cameras approximately 500m from any other camera. These grids will be established at four locations within the south-east of Tasmania (total of four grids, equalling 64 cameras for the whole study). These cameras will be left for three months without baits (for acclimation) before being serviced for the first time. 

The data captured from this three-month acclimation period will be compared to data collected by 110 pre-existing camera traps currently operating in the same areas within the south-east of Tasmania, generally within 1km of the planned grid sites. These cameras have been placed strategically along roads and trails for a different experiment within the DEEP research group which was started in 2018. To clarify, we are not requesting approval for these 110 cameras, as they have already been approved and are currently deployed (UTAS Ethics number: A0017229, DPIPWE Permit Authority No. FA 19056). 

The rates of capture and proportion of days occupied by feral cats, as well as the accuracy of density estimates made for feral cats, will be compared between some of these 110 strategically placed cameras and the newly placed systematically distributed grid cameras. This will allow us to determine which method of placement is most appropriate for feral cat monitoring, both in terms of the accuracy of their estimates and for efficiency and field time.

For aim 2. To compare passive camera-trap detection rates with camera traps baited with a variety of visual, olfactory and food lures, as well as unbaited cameras, and to determine which baits, if any, are most effective: 

To clarify, the strategically places, pre-existing 110 camera traps will not be needed or used in this part of the experiment. They are only required for comparison with the grid cameras when they are unbaited within the acclimation period. 

After the three-month acclimation period, the camera traps will be serviced and lures placed. This will involve changing the SD card and batteries of the camera trap, checking for errors, and repositioning the camera if necessary. Then, the cameras will be baited with either a food lure (e.g., wallaby meat sourced from a pet meat supplier held in a canister), olfactory lure (e.g. Puffinus tenuirostris oil scent), or a visual lure (feathers), or they will be left unbaited. Wallaby meat will be placed in bait canisters, making it difficult to obtain. These lures have been chosen as they have previously been thought to attract feral cats (Read et al., 2015), though they may also attract devils and spotted tail quolls who share a similar carnivorous diet. Lures types will be changed each service, so that any one camera will have a different treatment each month. The cameras will be serviced every month for four months. 

The lure will be positioned in front of the camera trap, so that we may capture animal response and potential lure destruction/consumption. Only images captured prior to lure destruction/consumption will be used if these events occur. Time since lure deployment will also be recorded and used as a predictor for feral cat detection rate. This will allow for a deeper exploration of how lures can be used more efficiently. 

After four services, the cameras will be removed. No animals will be handled throughout the field campaign. Human impact will be minimal within the field, limited to the placement of the lures and attendance to the camera servicing. Sites that require minimal disturbance of flora (such as natural arenas and game trails) will be sought for camera placement.

Fate of animals: No animals will be captured. They will be automatically photographed when they pass a camera trap.  

Likely impact on species involved (including any by-catch): Based on past data, both native species and feral cats seem largely unperturbed by the camera traps, whether white-flash or infrared is used for night images. If an increased number of cats and devils do visit the cameras, it may disrupt the foraging routine of some native species. Otherwise, impact should be minimal. 

Scientific Research Permits
Natural and Cultural Heritage
Level 5, 134 Macquarie Street
Hobart TAS 7000
Email: Scientific.Permits@dpipwe.tas.gov.au

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