THE NUMBERS OF ANIMALS 105 



and not up the side of cliffs. If one examines the photographs 

 of Adelie penguin rookeries given in antarctic books of travel 

 (e.g. by Mawson ^^ for Macquarie Island), one can get a vivid 

 idea of the numbers of birds involved. Imagine several 

 million short gentlemen in dress clothes (tails) standing about 

 in a dense crowd covering several square miles of otherwise 

 barren country (see photo in Plate VII (b)). Viewed from a 

 height they look like gravel spread uniformly over the land, 

 with dark patches at intervals to mark the areas of tussock 

 grass, which stand out as islands in the general ocean of 

 penguins. 



In both these latter examples^ — the penguins and the 

 guillemots — the birds represent the numbers from a very 

 large feeding area concentrated in one place for breeding 

 purposes ; and to this extent they do not give a fair idea of the 

 normal density of the population. 



7. If we turn again to Africa, not this time to the rivers 

 but to the open grass plains and savannahs, we shall find in 

 some places vast herds of hoofed animals — zebra, buffaloes, 

 and many kinds of antelopes. These are sometimes amazingly 

 abundant. Percival ^^® records seeing a herd of zebras in close 

 formation which extended for over two miles, and other 

 observers have recorded similar large numbers in the case of 

 other animals. Alexander Henry j^*^ describing the abundance 

 of American buffalo in one place in 1 801, wrote in his journal : 

 " The ground w^as covered at every point of the compass, as 

 far as the eye could reach, and every animal was in motion." 

 A hundred years later the bison was reduced to a small herd 

 kept in a national park.^'^ The fate of the American bison is 

 only one example of the way in which advancing civilisation 

 has reduced or exterminated animals formerly so characteristic 

 and abundant. The bison has practically gone ; the passenger 

 pigeon has completely vanished ; but in 1869 a single town 

 in Michigan marketed 15,840,000 birds in two years, while 

 another town sold 11,880,000 in forty days.^^ The Arctic 

 seas sw^armed with whales in the sixteenth century, but with 

 the penetration of these regions by Dutch and EngHsh whalers 

 the doom of the whales was sealed, and in a hundred and 



