Information on building your simulations
The first step is to define the boundary of the area over which you wish to simulate predator control, either by drawing the simulation area on the interactive map, or by uploading an ESRI shapefile.
On the second tab (Pests), select your target species (either possum, ship rat, Norway rat, stoat, ferret, or weasel), and the previous level of control that the area has received. This combination will pre-populate an approximate minimum and maximum number of pests that may be in the area: these values can be adjusted based on your knowledge. Other advanced species-specific parameters are automatically set, including: average home range size of individuals, carrying capacity (the maximum possible population size in a defined environment), and annual population growth. If you choose to simulate population growth, you will need to set a start day and duration of the annual reproductive period. These default parameters values can be altered by the user if more specific local information is available.
The third tab (Scenarios) is where you specify various control strategies, termed "scenarios". Each scenario will have a start and end date that defines the period of pest control. Next, select the device type(s) you wish to simulate for that scenario (a scenario can include multiple device types). The list of available devices will be specific to each species and will include traps that have passed National Animal Welfare Advisory Committee (NAWAC) testing for the selected species, as well as those that are intended to be used for the species, but have not passed NAWAC testing. For each device type, the user specifies the number of devices, the servicing interval (the number of days between checking and resetting devices), the number of devices that can be serviced per person per day, and the labour cost per person per day for setting and/or checking devices. Note the cost per device is preloaded but is indicative only - it is based on available information; however, different retailers may sell devices at higher or lower prices.
Once defined, the user can specify multiple alternative scenarios to reflect different control strategies, e.g. by varying factors such as the number and type of devices, the deployment length, and the checking interval. There is the option to clone a scenario and then make minor adjustments rather than having to specify all the parameters from scratch. You can come back to the Scenarios tab to add, remove, or edit scenarios. However, editing a scenario will overwrite your previous simulation result.
Once all the scenarios have been specified, click the "Run Simulations" button. Each scenario will be run sequentially over multiple iterations. Each iteration begins by deploying the devices across the landscape, and randomly locating the home range centres of each individual of the target species. The daily capture probability of each device+individual combination is calculated as a function of the distance between them, the home range size, and the interaction probability (see Gormley & Warburton 2017 for technical details). For each simulation night, the app will determine the fate of each individual (i.e. whether killed or not). Devices that reach their capacity (e.g., if a trap is sprung) will be out of action until the next checking interval.
For each scenario, a range of outputs will be generated including the percentage of the population removed, the cost of the scenario, and an 'Efficiency Index' which is a combination of the two - a higher index represents a more cost-effective scenario and is obtained with a lower cost and fewer animals remaining. It is useful for making quick comparisons between scenarios.
If you would like to save a copy of your simulation results for your reference, you can choose to either print the results or elect to 'Save to PDF' from your browser's print screen.
Gormley AM, Warburton B. (2017). TrapSim: A decision-support tool for simulating predator trapping. Landcare Research Contract Report LC2993