THE AMPHIBIA OF OKLAHOMA 



Harper's paper on Ps. orncita (1937), appearing while I was actively 

 engaged in studying the closely related Ps. streckeri, stimulated an attempt 

 to secure data on rate of calling. The results demonstrated that temperature 

 of both air and water influenced this rate as well as the interval between 

 calls; but neither seemed to affect the duration of individual calls. It was clearly 

 evident that other factors also were involved (Bragg, 1942). 



Since that time, I have kept a record for all species heard, based upon 

 (1) the number of calls per unit time, (2) the interval between calls, and 

 (3) the duration of each call at the air and water temperatures prevailing. 

 This has been done by timing with a stop watch at many of the breeding 

 congresses being studied for other purposes. Time of day has also been noted, 

 the record being based upon the time when observations at a given place 

 were started. It has usually taken from ten minutes to two hours to complete 

 each set of observations, depending upon conditions. 



In the present paper, I present in Tables I-VII a summary of data so 

 obtained. Additional similar data for Pseudacris triseriata have recently been 

 published (Bragg, 1948) and also a smaller number for Microhyla (Bragg, 

 1949). 



It is inherently more diflicult to secure reliable data on some species than 

 upon others by the method used. In some breeding congresses the calls of 

 one species may make data on others difficult to secure. Also, timing of inter- 

 vals presents a more difficult problem than timing of calls. For these reasons 

 more data have been secured on some species than on others, as is reflected 

 in the tables. 



Those for which data adequate for analysis on calling rate have been 

 secured are Hyla v. versicolor,- Microhyla carolinensis ohvacea, Pseudacris 

 clarion, Ps. strec\eri and Ps. triseriata. 



For H. V. versicolor little need be said. The mean rate on 144 individuals 

 was just over three calls per ten seconds, the range, 2-4 and the mode, 3. 

 Within the range of the temperatures observed (16.5°-20.0° for air, 17.0°- 

 22.0° for water, with the respective means, 17.5 and 19.3) there is very little 

 departure from the modal value 3 irrespective of the size of congress. The 

 duration of each call is short but the variation is considerable (Table M). It 

 is clearly not wholly a matter of temperature, however. For example, when 

 AT = 16.5° and WT = 17.0° C. (item 8), R — 1.0-1.5, varying about a 

 mean of 1.1, the mode, 1.0. But with only fifteen minutes difference (in time 

 of day) in starting observation, item 10 does not compare well at all, both 

 the mode and mean being only 0.4 with both AT and WT only slightly 

 higher than in item 8. If item 7 is compared with these, the discrepancy is 

 all the more apparent. The interval between calls is still more variable (Table 

 VII), the extreme fairly comparable, in individual cases, with the over-all 

 range for sixty-six observations. While we need further data (at lower tem- 

 peratures, particularly) the facts as they stand show a short rhythmic call, 

 varying in duration and interval irrespective of cither air or water tempera- 

 tures within the limits observed. (Jeneral observation indicates for this species 

 -As interpreted recently in Okl^ilionia (Bragg, 1948a.) 



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