THE AMPHIBIA OF OKLAHOMA 



patterns. April, 1947 was selected and the results are given in Table III. Rain- 

 jacent states. Most of the observations were made by me personally, but a 

 few came from other observers whom I know to be competent. I am especially 

 indebted to Mr. Harold Dundee, and Dr. Charles C. Smith, both of whom 

 have contributed to the data. All doubtful items have been eliminated, what- 

 ever their source. 



There appears to be a clear-cut, over-all tendency for most breeding to 

 occur during the period, April 16 to June 15, and for many species to breed 

 together. Mixed congresses are the rule. However, some species do not con- 

 form. Pseudacris strec\er'i, for example, has been found breeding only three 

 times after May 15 out of a total of 164 times. While the records are few, 

 Bu]o tvoodhousii jowleri has been recorded only in May and June. This is 

 also true of Microhyla carolinetisis carolinensis except for one record in the 

 first half of July. These species seem to have some seasonal restriction in breed- 

 ing. On the other hand, forms like Bufo cognatus, B. w. tvoodhousii, Pseu- 

 dacris clarJ{ii and, especially, Rana berlandieri show less restriction. Not only 

 do they start earlier but they end later than many other forms. 



Elsewhere, I have emphasized that the frogs and toads of Oklahoma are 

 influenced differently by the amount and rate of rainfall. All are stimulated; 

 but some respond only during certain periods of the year. Others breed during 

 rain at any time when temperature is high enough to permit it. This must be 

 taken into consideration in interpreting Table I. For example, the record for 

 Bujo cognatus (143 items) is approximately the same as for B. w. tvoodhousii 

 (147 items) and the over-all period utilized is about the same (March 28 to 

 August 9 for B. cogtjatus and March 24 to September 4 for B. tv. tvoodhousii^. 

 Most of the breeding for each occurs from April 1 to June 1 but the percentage 

 difference is approximately 21 ( 134 = 93.7-]-'^ o for B. cognatus, 107^ 

 72.8 — % for B. tv. tvoodhousii). Inspection of Table I will show that some 

 of this difference comes from more congresses in late March and August for 

 B. tv. tvoodhousii than for B. cognatus. Opportunity for convenient observa- 

 tion probably accounts for most of the remainder. 



Field observations show that all of the 143 items recorded for B. cognatus 

 have been after rain at temperatures, 12°C. or above. Those of B. tv. tvood- 

 housii have also been after rain except twelve and at temperatures 13°C. or 

 above. On several occasions, B. tv. tvoodhousii has not called at 12°C. after 

 rain when B. cognatus was breeding; and on eight occasions B. cognatus has 

 failed to breed after rain below 12 °C. 



It is on the basis of such observations as these that I have suggested the 

 breeding patterns, outlined without supporting data in earlier papers (Bragg, 

 1944-45, 1946). I have been particularly impressed by the distribution of 

 these patterns in relation to ecological distribution of the various forms. 



I thought that it would be instructive to select one month arbitrarily 

 (out of the many for which I have adequate records) to illustrate the relation 

 of breeding to rainfall. This was not selected to show this relation best, and 

 I had no idea what the details would indicate except, naturally, the confidence 

 that they would support my general impression as to validity of the breeding 



36 



