SOME INDIRECT RESULTS 501 



is also prevented by them from recuperating in its old age. 

 Thus there has resulted a general decay of forests bordering 

 the heath and moorland pastures of sheep, the limit of the 

 growth of forest upon the hillsides has been lowered, and 

 woodlands have been forced down the mountain sides into 

 the sheltered valleys where more rapid growth helps to 

 counteract the influence of herbivorous enemies. 



Such a consequence of the introduction of new animals 

 is so gradual in development that it is scarcely noticed amidst 

 a confusion of causes and effects. But St Helena offers a 

 vivid presentment of its stages. When it was discovered 

 by the Portuguese in 1502, the island was covered with 

 luxuriant forests and a rich assemblage of peculiar plants. 

 Goats were introduced in 1513 and multiplied rapidly ; then 

 native plants and even the tropical forest began to disappear. 

 yet even in 1709, the native ebony was so abundant that it 

 was used as fuel for burning lime. With the enormous in- 

 crease in numbers of the Goats, however, new forest growth 

 ceased, and when the older trees had been cut down by man, 

 it was realized, in 1810, that the forests were gone, leaving 

 no successors to take their place. The island, which was a 

 precious oasis of tropical plant life set in the midst of the 

 Atlantic, has become a barren and rocky waste. 



Results of similar nature, but on a less noticeable scale, 

 have followed the introduction of Sheep, Goats, and Rabbits 

 in Scotland, and the destruction of the forest, for which they 

 were in part responsible, set in motion many trains of cir- 

 cumstance, the origins of some of which have been traced 

 in an earlier chapter. 



THE CASE OF GULLS AND MOORLAND 



Of necessity these pages have been confined to the main 

 currents of man's influence, but it must not be supposed that 

 his little, insignificant interferences pass unnoticed in the 

 world of nature. Since it has been impossible to illustrate 

 these step by step, it must be taken as sufficient and as 

 typical of many others if I trace a single particular case that 

 o'f Gulls and the Moorland, to which my attention was 

 drawn by Mr O. H. Wild. 



In the northern confines of Peeblesshire, on the southern 

 slopes of the Pentland Hills, there is a considerable area of 



