156 ECOLOGY AND LIFE HISTORY OF THE COMMON FROG 



language as it has been handed down to us, and not really likely to 

 confuse anyone reading this kind of book. In case, however, there is 

 anyone who believes, when I say that the female frog **can get rid 

 of the male any time she wants to" that I am suggesting that something 

 hke the balcony scene in Romeo and Juliet is enacted in a frog pond, 

 I should explain that although the basic principles are the same, I do 

 think that what happens there is cruder. 



With this theoretical digression, we can proceed with a description 

 of what actually happens in the pond, with, I hope, the added interest 

 of watching for the directiveness, the psychology, and the step-by-step 

 analysis. 



In the last chapter, we arrived at the point of spawning, but we must 

 retrace our steps a little, for the events I am now about to describe 

 really begin during migration. In some years, but not in others, there 

 is a stage that I have called (1935) the "pre-spawning period." On 

 such occasions, if a pond is approached at night with a light, male frogs 

 will be seen gathered at the spawn sites, usually in the shallows, resting 

 with their heads out of water, but quiet and motionless. The numbers 

 increase night after night, but there is still no sign of breeding. There 

 may even be pairs in amplexus, but no eggs are laid. In one pond, 

 Large Totteridge, I watched this going on every night, and I believe 

 that I was present when breeding actually began. It was a sudden 

 event. At 8.30 I was at the pond alongside the road, and found that 

 all was quiet, although there was much migration. I then went on to 

 the farm that borders the pond and is separated from it by a high fence. 

 While I was there, I heard croaking for the first time that year. Because 

 of the high fence I had to make a long detour to reach the pond, and 

 did not arrive for about ten minutes. By the time I did so, at 9.30, 

 croaking was in full swing. Slight rain had just started. The important 

 point is that the chorus struck up as if at the motion of a conductor's 

 baton, after seventeen nights had elapsed since I saw the first frog 

 sitting in the pond, waiting for something. The rain may have had 

 something to do with it, but we know quite well by now that frogs 

 behave in much the same way all through a drought, so that the rain 

 cannot be an essential sign-stimulus. It is quite possible that when one 

 frog starts all the others follow, but this only transfers the problem — 

 what makes this frog start? It is, I suggest, something that happens in 

 the pond, which in other years has already happened by the time the 

 first frogs arrive, so that in those years there is no pre-spawn period. 



