find the rabbit and fox population as a function of time

#Find the rabbit and fox population as a function of time series

Domestic animals and herbivorous marsupials may benefit from lessened competition and there may be enhanced recruitment of perennial native plant species, some of which are highly susceptible to grazing by rabbits (see, for example, references cited in Williams et al.

There are many potential benefits of controlling rabbits in Australia. Therefore a range of possible epidemiological outcomes needs to be considered in order to assess the direct and indirect impacts of introducing RCD. Despite the widespread distribution of the virus and apparently substantial mortality rates in some populations of rabbits, the ultimate efficacy of RCD as a biocontrol agent for rabbits is not yet known. By the end of 1995, RCD was confirmed over much of the north-east of South Australia, in western New South Wales and the extreme south-west of Queensland. In October 1995, the virus inadvertently transferred to rabbits outside the enclosures and subsequently to mainland Australia. The trials used wild rabbits in natural warrens and were designed to measure mortality rates, persistence of the virus in the environment, and the humaneness of RCD.

#Find the rabbit and fox population as a function of time series

In 1995 a series of outdoor pen trials commenced in a quarantine area on Wardang Island in South Australia (B.D. These observations provided the impetus for RCD to be considered as a biological control agent in Australia, where rabbits are a major pest species ( Williams et al. Following the arrival of the disease in Spain, wild rabbits declined to 20–80% of their former abundance (B.D. Over the next decade the virus was detected in wild and domestic rabbits in Europe and central America.

In 1984 rabbit calicivirus disease (RCD) was reported to have caused high mortality in domestic rabbits Oryctolagus cuniculus (L.) in China ( Liu et al. For semi-arid Australia the model predicts that as the frequency and intensity of RCD epizootics increases: (i) the mean abundance of rabbits will decline, as will the frequency of eruptions of rabbits (ii) there may be little increase in mean pasture biomass and a small decrease in periods of very low pasture biomass when competition between herbivores is most intense (iii) the mean abundance of foxes will decline (iv) there will be a reduced frequency of occasions when rabbit density is low but fox density is high due to a lag in the response of predator populations and (v) there is potential for an increase in the mean abundance of alternative prey and in the proportion of time their density exceeds a threshold comparable to that currently required for eruptions of rabbits. In the absence of quantitative data for Australian conditions, the epidemiology of RCD was simulated empirically to mimic a range of potential patterns of occurrence.ģ. Similar dependence on pasture biomass was assumed for the dynamics of both rabbits and alternative prey in order to identify clearly the consequences of differing predation. A generic model for predation on native herbivores was constructed by modifying the density-dependent (Type III) functional response of foxes to rabbits to a depensatory (Type II) response that is appropriate for alternative prey. Existing data were used to quantify the interactions of foxes, rabbits and pasture. The consequences for fox populations that use rabbits as primary prey, for populations of alternative native prey, and for pastures, were examined using a model for rabbit- and fox-prone areas of semi-arid southern Australia.Ģ. Rabbit calicivirus disease (RCD also known as rabbit haemorrhagic disease) has been introduced recently as a biocontrol agent for rabbits in Australia.