62 The Pickerel-frog, Rana palustris LeConte. 



of second appearances, the maxima ranged from 48 to 62 degrees, aver- 

 aging 53 degrees. The water-temperatures of first appearance range 

 from 45 to 50 degrees. An average of all the first appearances is April 

 5, but a consideration of those from 1906 to 1911 gives April 3 as the 

 more accurate date. The range of records is from March 19 to April 25. 



THE VOICE. 



Of our Anura, this and the rather silent wood-frog make the least 

 audible disturbance at the breeding season. Its grating croak has 

 little carrying power and is pitched low; higher than in Rana pipiens, 

 but not so high as in Rana sylvatica, and it is more prolonged than that 

 of the wood-frog. It is so characterless that the tendency will be to link 

 it with a subdued Rana pipiens, but the latter has not so short a note. 

 The pickerel-frog note is not always given "while floating at the surface 

 of the water." I have heard it more often during the actual mating 

 than at any other season. The males of this species, like those of 

 Rana clamata and Rana pipiens, are much given to croaking beneath the 

 surface of the water while in the embrace. Quite frequently the un- 

 mated males croak beneath the surface and occasionally the males at 

 night appear to answer each other with a croak totally different from 

 the normal one. After the breeding season, it is seldom if ever heard. 



THE MATING. 



Usually the male is the smaller, but sometimes mated pairs have been 

 recorded where there was no appreciable difference in size. The male 

 is darker than the female; as in other members of the genus Rana, it 

 has the thumb enlarged at the breeding time; the webs of the hind feet 

 of the male are a little less concave at the margins than in the female, 

 though the difference is very slight. In mating areas some of the 

 unmated males may be darker than the mated ones, possibly due to 

 greater activity and greater exposure. Furthermore, the mated males 

 are sometimes lighter than their females, though not often so. 



Between first appearances and first matings, lengthy intervals elapse, 

 the least being 7 days, the longest period 32 days, the average 20 days. 

 The beginning of mating usually comes the last week in April, the 

 earliest record being April 5, 1910, the average April 23. This species 

 mates by day or by night. I have seen very vigorous matings at all 

 times of day. At this season it is one of our most gregarious frogs, and 

 is locally very much in evidence. It seems endowed with as much 

 nuptial ardor as any of our 5 species of Rana, and it is about the easiest 

 subject of the five to kill in the embrace all of which is in keeping 

 with its gregariousness. No other Rana while breeding is quite so 

 oblivious of intruders or so easy to observe as the pickerel frog. Often, 

 within a small area 6 feet square or less, one can find 12 to 15 pickerel- 

 frogs mating or pairs in egg-laying positions. Any sudden movement 



