

VIII ^, 



Frequency of Sex C>alls in Some Salientia 



ARTHUR N. BRAGG 



1"^HE following facts are very well recognized: (1 ) that male salientians, 

 under the influence of proper stimuli, use a call (usually distinctive 

 . for each species) in their attempts to secure females at breeding sites; 



(2) that there is some variation in the lengths of individual calls under dif- 

 ferent environmental conditions and physiological states of the organism; 



(3) that only males give such sexual calls; (4) that females respond to these 

 calls as though attracted to the male by them; (5) that males often are affected 

 by the calls of other males ( usually taking the form of further stimulation 

 of them); and, (6) that in some species the female also has a voice which 

 is used during sexual activity (its functions difier from the breeding call of 

 the male); in other species, females are completely silent during breeding. 

 In addition, males of certain species (and both sexes of others) make dif- 

 ferent sounds at various times. The so-called protesting notes of various 

 species of Bufo and Scaphiopus are example of one type, and the scream of 

 certain frogs (Rana) when injured represent another. 



Various observers have concluded that the sexual call of the male varies 

 in rate according to temperatures, social factors, and physiological states. 

 Thus, Harper (1937) reported that air temperature influenced this rate in 

 Pseudacris ornata Holbrook practically as a straight line function for the 

 few records that he could obtain. Bragg (1940, 1942. 1943, 1944-45)has 

 shown that, in several forms, males are stimulated by the calls of their own 

 kind and that in sonie, at least, the rate of calling is affected by the numbers 

 calling at any one time and place. To me, this has seemed clear-cut in Bu]o 

 cognatus Say, B. tv. woodhousii (Jirard, B. compactilis^ Wiegman, Pseud- 

 acris darken Baird, Ps. strecl{eii Wright and Wright, Ps. triseriata Wied, 

 Hyla versicolor versicolor LeConte, and all four of the species of Scaphiopus 

 studied in Oklahoma and New Mexico. I strongly suspect it in all other 

 species which I have often heard calling and the phenomenon may well 

 prove to bs universal in the group. 



One of the difficulties in studying the calls of Salientia has always been 

 the next to impossible task of describing differences in calls. To one familiar 

 with the characteristic call of a given species, a variation may be striking but 

 when he tries to put this in writing he usually ends up with unconvincing, 

 vague statements, apparently based on mere impressions. Quantitative data 

 have been needed. 



^ The only form of this s[iecics seen by the author at breeding is that called B. coin- 

 pMtilis speciostis by Smith ( 1947). 



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