Describe the interrelationships between the rabbits and the other species on the South Downs, and so explain how and why the local vegetation changed after the myxomatosis outbreak.
The South Downs, which is chalk grassland, extends from Winchester in Hampshire to Eastbourne in East Sussex. On the South Downs there is a rich diversity of plants and animals. A species of the South Downs is the european rabbit, Oryctolagus cuniculus which was introduced into Britain in the Middle Ages.
The first thing to look at is the interrelationships between the rabbits and other species. Rabbits are herbivores, primary consumers. They are highly selective grazers that concentrate on the most nutritious plants and keep the surrounding vegetation short. The elder bushes were unpalatable to the rabbits. Grazing by rabbits can be very beneficial to maintain the diversity of the habitat.
The animals that benefited from this are the stone curlew, a species that favours to dwell in short grass. Another species of bird, the wheater, benefited from the behaviour of rabbits as they use discarded rabbit holes for nesting. An insect that relies on the rabbit population is the minotaur beetle. The dung produced by the rabbits is used by the minotaur beetle larvae for food.
Rabbits act as competition for the brown hare, other herbivores and other grazing animals as they all compete for food and territory. The scratching around for food and burrowing of the rabbits exposed areas of bare chalk, which encouraged the establishment of weeds such as nettles, thistles and ragwort. Trees could not become deep-rooted because the rabbits damaged or killed them by eating the leaves. Trees grow from the tip down. When trees die, they decay and the nutrients are returned to the soil and utilised by other flora. This process is part of the food chain.
When the myxoma virus was...