36 The Peeper, Hyla picker ingii (Holbrook). 



the marsh was frozen solid; on March 13, 1911, the record of appear- 

 ance occurred in a marsh completely covered with ice. Air and ground 

 temperatures are the controlling factors. Often, with favorable sun 

 exposures, a side-hill where peepers are first heard may be several 

 degrees higher than the air. For example, their first appearance on 

 the university campus in 1911 (March 27) occurred on a side-hill with 

 eastern exposure under air- and ground-temperatures of 54 degrees and 

 60 degrees respectively. 



THE VOICE. 



The peeper is most vociferous in the afternoon and evening, but 

 numerous records have been made of full choruses under a hot noon- 

 day sun. Nor is its note wanting in the early forenoon, for often the 

 first mating records were secured by following the notes of the morning 

 "peepers." In fact, when at the crest of the chorus stage (last of April 

 or first week of May), their din may be heard incessantly day and night. 

 Their notes are variable, but usually shrill, clear, and high-pitched, 

 and can be heard at a distance of half a mile. Often an individual 

 male calls 15 to 25 times a minute, each whistle being a second or less 

 in duration. This species even more than its congener, the tree-toad, 

 semi-inflates its vocal sac during its silent intervals. Often when we 

 have suddenly captured them thus swollen, the collapse is accompanied 

 with a curious squeak. 



During the chorus-stage, the male in the pond has a very different 

 note from one approaching it. The note of the latter lacks the strength 

 and volume of the male already arrived and has a more querulous 

 tremor in it. It is interesting to observe how suddenly a chorus will 

 end at one's approach, only to be soon resumed if the intruder remain 

 quiet. At this time, they may be among the grassy hummocks along 

 the sides of the ponds, or in the shallow pools within the surface film 

 of dead leaves or algae. Not infrequently when disturbed they may 

 be seen leaping on this matted carpet before disappearance. In one 

 instance we discovered one in the spathe of the skunk-cabbage. They 

 may be taken at night with a flash-light without much effort, be they in 

 grass, trees, or ponds, provided they "peep" occasionally. It is gen- 

 ally about 3 to 6 days after the first record, that the first chorus is 

 noted; the extremes are 1 and 23 days. The records are given in the 

 table on page 37. 



In six of the ten records we observe, on both sides of the record, 

 maximum temperatures of 60 degrees or more; in every case, 60 degrees 

 or more on one side. Certainly the lone 54 degrees is a conservative 

 temperature for the beginning of the chorus-stage. Of numerous air- 

 temperatures taken at times of choruses, 52 degrees is the lowest 

 secured. When the thermometer begins to ascend through 60, 70, 

 and occasionally 80 degrees, as it does in the last two weeks of April, 

 and from May 1 to 16, we have the crest of the chorus-stage; after the 



