96 ECOLOGY AND LIFE HISTORY OF THE COMMON FROG 



food preferences. The toad, B. bufo, learned to avoid bees by trial 

 and error, and Cott considers that this form of natural selection has 

 contributed to the evolution of such modifications as warning colora- 

 tion in insects. 



The feeding habits of frogs, as distinct from the nature of the food 

 found in the stomach, have been very little studied. It is sometimes 

 said that the animals *'hunt" or *'forage." In fact, however, they 

 seem during the day to remain in their hiding place, fully alert, and take 

 any suitable prey that comes within the short range of their not very 

 good eyes. A worm ten or fifteen inches away may pass unnoticed, 

 but if it is moved nearer to, say, three inches it may be eaten at once. 

 Now this cannot be called hunting — it is far too passive. On the other 

 hand, it is more active than the fishing of a sessile animal such as the 

 barnacle, which puts out its net and takes in anything that passes. Per- 

 haps the nearest human analogy is that of the wild-fowler who places 

 himself where he thinks the birds will come, does nothing to make them 

 fly over, and shoots when they come within range. In both cases, 

 success depends on the right selection of the place to hide in, at least as 

 much as in the accuracy of the shooting. At night, however, the fiogs 

 wander. It may be true that these wanderings are for feeding, but, 

 as usual in amphibian movements, they stay still for such long periods 

 that it is surely questionable whether they meet with more food in a 

 given time than if they kept still. Perhaps they are merely moving out 

 from a place depleted of food by their day-time feeding, or moving 

 into an area populated by nocturnal prey but not abundantly suppHed 

 with food in the day-time. On these questions there is room for some 

 good, old-fashioned natural history observations, with pencil, note- 

 book, and watch as the instruments. With a frog in its natural hiding- 

 place as the object to be studied, and a team of patient observers who 

 would watch and time events round the clock, we might achieve "A 

 day in the hfe of a frog" of considerable interest. 



We seem to know rather httle about underwater feeding in this 

 species. Boulenger (1897) did not consider that the frog feeds at all 

 when under water, but here are two mutually supporting lines of 

 evidence to the contrary. Smith (1949) records that in frogs caught 

 in January and February, the larvae of aquatic insects were found. 

 Moreover, parasitologists say that the intermediate host of the intestinal 

 parasite, Acanthocephalus ranae, is the water louse, Asellus aquaticus. 

 When parasitology and ordinary observation agree like this, it becomes 



