54 The Leopard-frog or Meadow-frog, Rana pipiens (Schrcber). 



of April their notes begin to become common, and from that date to 

 May 1, or later, their calls are very common, even during the day. 

 By the middle of May, they are beginning to be heard only during the 

 evening. Sometimes in summer, during showers or on cloudy days, they 

 resume croaking ; for example, July 4, 1906, followed a rainy evening, was 

 cloudy most of the time, and Rana pipiens was heard throughout the day. 

 In the autumn they are rarely heard in the swamps, e. g., September 

 14, 1912. 



THE MATING. 



The mating habits of this species are doubtless more familiar than 

 those of any other North American frog. The males at the breeding- 

 season have the thumb much enlarged, but the webs of the hind feet 

 are not quite so convex as those of the male wood-frog. At the mating 

 period they are much darker than in early midsummer, the males 

 usually darker than the females. For example, on April 1, 1910, I 

 captured a mated pair in which both were very dark. The male was a 

 very clouded green in fact, as dark as any Rana pipiens just coming 

 out of hibernation, and the female a dark brown, but much lighter 

 than the male. These were exposed to the direct rays of the sun for an 

 hour in a glass jar. At the end of this period, the male was a typical 

 grass green of the summer coloration and the female a very light brown- 

 ish green. As evening came on, they became darker again. 



The period of mating begins April 1 , or before ; but the bulk of it does 

 not come until the middle of April, and it continues for about three 

 weeks, extending to the first or middle of May. 



This species is not restricted to night courtship, although most of 

 it occurs at this time. One can frequently observe the mating antics of 

 this species in the day, if he can discover a spot where the species has 

 already begun ovulation. In such localities we have taken most of our 

 mated pairs. Before they are mated, here at the surface, the males are 

 croaking. Occasionally, when wading through such an egg area, one 

 hears croaks which at first puzzle; they come from the mated and 

 mating frogs beneath the water and often reveal the game on the bottom. 

 At such times one finds several males and gravid females about and 

 under sticks. More rarely the pairs appear at the surface. 



In the field the embrace probably does not last over a day or so. 

 In many instances egg-laying followed immediately, the night after the 

 capture; in several cases it came after 2 or 3 days. In pairs mated in 

 captivity (usually unfruitful), we have recorded long periods of mating. 

 One pair continued five weeks in the embrace, the male dying because 

 the water was not changed. In another case a male so held a female 

 17 days, and upon her breast, where the two hands had been placed, 

 were round scars (Plate iv, Fig. 3), the flesh being exposed. Not as 

 frequently as with the toads, does the female die because of the vigor 



