l60 ECOLOGY AND LIFE HISTORY OF THE COMMON FROG 



them with a groAving sense of apprehension, feehng that I had been 

 completely anticipated in my work. In the end I found that my 

 predecessors had left something for me to describe. I do not think that 

 the other accounts in the literature are original — they are not claimed 

 to be, and occur in contexts in which compilation was to be expected. 



The Events in the Pond 



For the field study I selected a suitable pond, and made observations 

 almost every night of the season. Frogs at night pay httle attention to 

 an observer behind a light, and continue with their breeding behaviour 

 in its beams. Artificial light has appeared too late in their evolution 

 to have any meaning for them, and, as with many other animals, it is 

 only events that have mattered in their history that have left responses 

 in the animals. Moreover, they are only temporarily affected by day- 

 time disturbances. On one afternoon during the observations, I passed 

 the pond and saw with alarm that some boys were punting violently 

 across the very spot where I hoped to be that night. I need not have 

 feared. As I walked up to the pond that night, I heard the famihar 

 croaking, and there were the frogs, not merely any frogs, but the 

 labelled individuals that I was observing. Frogs must have been dis- | 



turbed for thousands of years by large animals coming down to drink 

 at the shallow places that they choose for spawning, and the boys do J 



not represent anything essentially different. 1 



Many of the frogs were tagged with small paper labels, large enough ' 



for the numbers to be read in many cases without even catching the 

 frog. I could therefore make a roll-call by standing among them and 

 writing down the numbers as they swam about. There were usually 

 about sixty frogs present each night of the season, which lasted for 

 twelve nights. I was present for eleven of them, usually for about two 

 hours on each night, so that I probably saw most of the typical be- 

 haviour. Table 9 shows the results. Several males secured more than 

 one female in the season. The frog A18 was mated with a different 

 female on each of three successive nights. Since the numbers of the 

 sexes are about equal, this must imply that other frogs do not secure 

 a mate at all in that year. It can easily be seen how important it is for 

 a male frog to arrive at the pond in good time, for otherwise his chances 

 of leaving offspring are much diminished. This functional polygamy 

 also goes far to explain the intensity of the competition between the 

 males, of which I shall have more to say later in this chapter. With 



