Erinaceus europaeus, the hedgehog, is a small carnivorous mammal native to Northern Europe. In 1974, hedgehogs were brought to a small cluster of islands off the west coast of Scotland. Their numbers have risen so that there are now more than 5000 breeding pairs. These hedgehogs have no natural predators on these islands and their diet consists mainly of birds’ eggs. Fig. 8.1 depicts a hedgehog. Fig. 8.2 illustrates the hedgehog population density in the year 2000. Table 8.1 presents the changes in the populations of the species of birds from 1983 to 2000.
(a)[3]
Using Fig. 8.2 and Table 8.1, describe how hedgehog population density is related to the changes in the populations of lapwings and redshanks.
(b)[2]
Suggest an explanation for why the oystercatcher population on the south island increases, even though the hedgehog population also increases.
(c)[4]
Explain why the population of hedgehogs on one of these islands may eventually become a different species from that on mainland Scotland.
Worked solution & mark scheme
This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: “north island: fewer hedgehogs leading to an increase in lapwing and redshank” …