Part Objective 1 Effectively control feral ca - Threat Abatement Plan for Predation by Feral Cats - Objective 1 Effectively control feral cats in different landscapes | Zoe
Objective 1 Effectively control feral cats in different landscapes
Predation by cats is a threat that needs to be interpreted and managed according to the landscape type and particular pressures in the area being managed. The landscape in which feral cats are being managed will determine which tools are most effective to use (for example, management in an alpine boulder field will be quite different to a tropical floodplain). Timing of management is also critical to achieve threatened species protection (for example, timing to protect ground nesting birds, or in anticipation of or at the end of mouse/rat/rabbit plagues when the abundant feral cats are switching to other prey resources such as small threatened mammals). Site specific characteristics also need to be taken into account including the potential for immigration of new cats to the area, other management actions that are being undertaken (for example, prescribed burning) and other predators being controlled (for example, European red foxes) or conserved (for example, dingoes). The degree of control required to achieve the desired outcome (for example, recovery of threatened species) must also be determined. Ensuring the management plan is interpreted and appropriately implemented for the area is important so that control programs for feral cats achieve the outcome of reduced predation of threatened, near-threatened and other native species.
While this threat abatement plan is focused on the impact on biodiversity, feral cats also have an impact on agriculture through spreading disease and on tourism by reducing the numbers of unique Australian species to be seen.
This objective builds on two ongoing research streams: first, research into new control options that will reduce land managers’ expenditure on time-intensive, skilled labour; and secondly, research on the roles of feral cats within landscapes and how a range of land management practices may be used or manipulated to exert additional pressure on feral cats. This can include possible suppression by other predators, exploitation by feral cats of phenomena such as fire and prey irruptions, the sites to which cats and/or their prey retreat during tough times such as drought, and the role of cat-borne diseases. When research and development are being undertaken, evaluation of the success of control options for feral cats needs to consider how the biodiversity outcomes can be monitored as well as knowing how many feral cats have been killed or the change in their abundance/activity.
Action 1.1 Ensure broad-scale toxic baits targeting feral cats are developed, registered and available for use across all of Australia, including northern Australia
Land managers require effective tools for achieving feral cat control. These have been lacking on a broad-scale for feral cats with shooting, trapping and fencing being the main options available.
In 2014, a toxic bait (Eradicat®) was made available for use on Western Australian lands managed by or in agreement with the Western Australian Department of Parks and Wildlife, which provided an additional tool for that state. Eradicat® contains the toxin 1080 (sodium monofluoroacetate) directly injected to the sausage bait (Algar et al. 2013). The Eradicat® baits can be surface laid in southern Western Australia with minimal risk to native animals that may consume the baits because native species in this area have a degree of tolerance to the toxin. This is because some plants in Western Australia naturally contain the toxin allowing tolerance to develop in the native species.
In the rest of southern and central Australia, with the exception of Tasmania, a new bait (Curiosity®) is being developed for use. Instead of directly injecting the sausage bait, the Curiosity® bait encapsulates the toxin para-aminopropiophenone (PAPP) in a hard plastic pellet to reduce the risk to non-target native species that may eat the sausage bait. Most of these non-target species have been shown to reliably reject the hard plastic pellet while eating the bait (Department of the Environment 2015a). During the life of this threat abatement plan it is expected that the Curiosity® bait will be registered for use.
In northern Australia and Tasmania, neither Eradicat® nor Curiosity® are suitable for use due to risks to the non-target species of varaniids (goannas) and Tasmanian devils (Sarcophilus harrisii). However, a variation to the existing baits — Hisstory — is likely to be suitable. The Hisstory bait encapsulates the the toxin 1080 instead of PAPP, because varaniids and Tasmanian devils are tolerant to it. It is intended that Hisstory will be able to be laid where varaniids and Tasmanian devils are active but still provide protection for other non-target native species. The Hisstory bait still requires additional research and development.
There is additional information on baiting for feral cats in the background document and Department of the Environment website.
It should be noted that with all of the toxic baits it will be necessary for land managers to determine the risk to valued, non-target fauna at a particular site based on guidance from bait manufacturers. As with any feral animal control tool or program, it is not possible to reduce all the risks to zero, and land managers must consider this in designing their baiting programs. Specifically, dingoes may be at risk if multiple toxic baits intended for feral cats are consumed.
As with Eradicat® baits, governments will be required to restrict access to toxic baits and areas of application in order to maximise target specificity of baiting programs for feral cats, similar to other introduced predator control programs. Bait suppliers will also need to ensure that users understand the suitable environmental conditions for putting out baits so that they are effective.
Action 1.1 seeks to ensure that toxic baits are registered and available for feral cat control across all of Australia. It should be emphasised that baiting is not the complete answer to feral cat control but rather is another promising tool which can be applied in a broad-scale manner.
Action 1.2 Develop and register other cat control tools, including devices exploiting cat grooming habits
Action 1.2 recognises that scientists have been investigating a number of devices for cat control utilising particular traits of cats such as their fastidiousness for grooming. The designs of these devices are able to distinguish non-target species. These tools may be particularly useful in some locations where cat activity in the landscape is restricted; for example along animal trails through thick vegetation or alongside watercourses, or where non-target species are vulnerable to other control techniques (Moseby et al. 2011). Another potential techniques being investigated is using encapsulated toxin implanted in threatened species or collars on the threatened species containing a toxin to kill any feral cat or other predator that may specialise in predating upon that threatened species. As with Action 1.1, this action focuses on getting these tools to land managers for use within cat control programs. Although not an explicit action, ongoing improvements to the design and operation of existing management options for feral cats are also important. Exclosure fence designs are an example where refinements continue to be made for different situations.
Action 1.3 Continue research into understanding interactions between feral cats and other predators: (i) in different landscapes; and (ii) any potential beneficial/perverse outcomes if other predator populations are modified
Feral cats have natural enemies or competitors in the other mammalian predators – the European red fox, wild dogs/dingoes (Canis species) and Tasmanian devils will all kill feral cats. These species and quolls will compete with feral cats for food resources. Section 1.3 in the background document provides information on competition between feral cats and other species. For the purposes of this threat abatement plan wild dogs and dingoes are considered together because they freely inter-breed and there is a continuum of animals across the continent that contain varying degrees of dog and dingo DNA (Stephens, 2011). A great deal of recent research has focussed on interactions between feral cats and these other predators. Section 3.3 in the background document provides further information about the relationship between wild dogs/dingoes and feral cats. Although much of this work is ongoing and is not conclusive enough to make any broad-scale recommendations, an important theme is that relationships between the mammalian predators can vary in space and time. In some places European red foxes and/or dingoes seem likely to suppress feral cats (i.e. their numbers, behaviour or both) whilst in other parts of Australia one species appears to have little or no affect on the other (e.g. Fleming et al. 2012; Johnston and Ritchie 2012a; Allen et al. 2014; Allen et al. 2014a; Kennedy et al. 2012; Greenville et al. 2014; Wang and Fisher 2012). Further understanding these relationships, through research, is the focus of Action 1.3 so that land managers can make informed decisions about predator interactions when designing and implementing effective local management programs.
Action 1.4 Continue research into understanding the role of other major landscape modifiers, such as fire or grazing by introduced herbivores, in feral cat activities and control
Other landscape modifiers such as grazing, woody weeds and introduced grasses have a less obvious impact on predation by feral cats. However, these modifiers can affect feral cat hunting behaviour and success in positive and negative ways. Cats will respond to changes in landscapes through population changes or activity changes, including in response to:
natural phenomena (for example: prey irruptions such as plague rat (Rattus villosissimus) and mice (Mus musculus) following good rains);
landscape management (for example: prescribed burning or land clearing); and
management programs for other invasive species (for example: an increase in rabbit numbers due to declining effectiveness of biocontrols may provide additional food for feral cats (Doherty et al. 2015)).
Research is providing insights into these responses, such as the preferential use by feral cats of areas recently burnt with high intensity fires to get easy access to prey species that have no vegetation cover to hide in (McGregor et al. 2014). This knowledge is valuable for land managers to adapt management programs for feral cats in order to exploit these responses, although this should not be to the detriment of the overall biodiversity outcomes sought. Action 1.4 seeks to provide what is known to land managers, and continue this research and provide it to land managers. Overlaid on the responses of feral cats to landscape changes is the changing climate due to global warming, which will need to be taken into account.
Action 1.5 Continue research into the scale, efficiency, cost-effectiveness, sustainability and risks of feral cat control options
When designing a program for feral cat management it is important to understand the scale of control required, the cost-effectiveness of the method/s being employed and their long-term sustainability. Action 1.5 is aimed at further improving our knowledge of how much and when to undertake control; the short and long term efficiency of that control, especially with feral cats immigrating from outside the site; the cost-effectiveness of the control for the threatened species (or other matter being protected) and what combinations of control methods may work best in different locations. Included in any program must be monitoring to understand the outcome for the program, such as the recovery of a particular threatened species. An element of this research is to examine the effectiveness at a suitable scale and the comparative cost of creating a feral cat (and other predator) free area through intensive predator control in the surrounding area to prevent immigration of new animals. The potential for perverse outcomes, such as low level control leading to an increase in feral cat numbers, needs to be understood (e.g. Lazenby et al. 2015). As mentioned in the previous section, this knowledge must focus on the recovery of threatened species as well as the control of feral cats. This information on program design should be provided to land managers in order for ongoing effective delivery of the management program.
Action 1.6 Continue development of new or enhanced attractants for cats to improve cat control and monitoring. Ensure availability of any attractants that are developed
Robust monitoring of feral cats can be difficult because of their dispersed spread and occurrence at low densities. In some circumstances it is necessary to use lures to attract cats into monitoring locations and control locations (e.g. traps). Although a range of visual, olfactory and auditory lures have been developed to attract feral cats; all lures are only partially successful. Action 1.6 identifies the development and assessment of other lures so that land managers get better results with their monitoring or control.
Action 1.7 Research into other control and monitoring technologies and enhancing available technology
Action 1.7 identifies the need for ongoing research into new control and monitoring tools. Included in the new control tools is support for the development or provision of humane killing methods, particularly for small community groups where the current options (e.g. shooting, lethal injection administered by a vet) are not available or are too expensive/inhumane.
There are two elements to the monitoring tools. Firstly, there is a need for simple, low cost and low effort monitoring tools for small community groups with few resources. These monitoring tools should be accompanied by education to ensure the community groups can use them effectively. These monitoring tools should be accompanied by education to ensure the community groups can use them effectively. Secondly, there is a need to develop or enhance cost-effective monitoring technologies for feral cats more broadly and, where possible, collate the results. Further to this, a greater understanding of the links between feral cat numbers and impacts will allow land managers to know the appropriate level of control required. Unfortunately, there may be instances where the majority of the impact is caused by one or two individuals that have specialized in a particular prey item (e.g. the threatened species).
Action 1.8 Re-investigate diseases and other potential biocontrol agents, biotechnology and immunocontraceptive options for cats, and commence research on promising options. Undertake social research on promising options to gauge community support
Biological control agents such as cat-specific diseases have been reviewed in the past (e.g. Moodie 1995). However, with new techniques, a greater capacity to gather international information, and the possibility of other emergent diseases, it is appropriate to undertake a new review to search for biological control, and immunocontraceptive options.
In addition, the field of biotechnology has platform technologies that may be applicable to feral cat sterilization. Outlined in the background document is information about the emerging technology of RNA-guided gene drives. While this technology is still only in its infancy for applications in vertebrate pest species there is potential for population suppression through guiding changes to particular genes that alter the sex bias of new animals or sensitize a species to a particular toxin. It should be noted that this is a long-term potential technology and is not likely to be realized for feral cat control within the life time of this threat abatement plan.
These ideas are captured in Action 1.8. The search for new biological tools, and any subsequent research on promising agents or biotechnology options, will need to consider the risk to and protections for domestic cats and to other felid species internationally should the agent or technology escape from the country. In addition, the potential suffering of the feral cats must also be taken into account as a biological control that involves prolonged suffering is unlikely to be accepted for release. If a promising agent or technology is identified, social research would need to be undertaken to ensure there would be community understanding and support for a potential release. An effective method for gauging community support could be via a deliberative process of decision-making (for example an iterative approach using a focus group or citizen jury to listen to experts, discuss the rationale for their views, and modify their views following the discussion and feedback).
Captured within this action is also the concept of an indirect control for feral cats through a reduction in abundance of some of their introduced prey species (ie. rabbit, black rat, house mouse), which may be done through improved biological controls for those species.
Action 1.9 Code of Practice and/or Standard Operating Procedures developed for new tools and agreed by governments
There is a nationally agreed Code of practice for the humane control of feral cats (Sharp & Saunders 2010) and Standard operating procedures for ground-shooting of feral cats, trapping of feral cats using cage traps and trapping of feral cats using padded-jaw traps (Sharp 2012a; Sharp 2012b; Sharp 2012c). As new tools become available the code of practice will require updating and new standard operating procedures may be required. Standard operating procedures will also require updating as technology (e.g. suitable firearms) changes. In particular, standard operating procedures are required for baiting with the different toxins, 1080 and PAPP, and for feral cat-proof fencing. Note that state or territory legislation must also be complied with when managing feral cats. In developing a new code of practice or standard operating procedure the tool should be assessed through the model for assessing the relative humaneness of pest animal control methods (Sharp & Saunders, 2008). Action 1.9 seeks these updates or new documents, consultation with all stakeholders (government and non-government), and endorsement by all governments through the national biosecurity system.