THE AMPHIBIA OF OKLAHOMA 



temperatures of 13° C. upward. The latter has a late but consistent breeding 

 season (late April through June in Oklahoma) at temperatures seldom below 

 21° C. Therefore, in any region where both species may occur, if one is 

 heard calling when the temperature is below about 20° C, it is almost certain 

 to be woodhousii. At temperatures above 20° C. or 21° C. in March to mid- 

 April and after |uly 1, it is again woodhousii. Of course, in the height of the 

 breeding season of jouderi (about mid-May) and at temperatures above 

 20° C. the two could not be separated on this basis. 



(2) In the leopard frogs, as emphasized previously in other connections, 

 the Oklahoma form diflers radically in breeding behavior from its counter- 

 part, Rana pipiens pipiens of the East and North, although differing little 

 if any morphologically. 



(3) Groups of spadefoots may be separated partially by their breeding 

 reactions; so, also, may species of Pseudacris. 



(4) Behavior and movements of tadpoles as seen undisturbed in pools 

 are also sometimes distinctive. Most larval Hylidae, and, to a lesser extent, 

 larvae of Microhyla, tend to spend considerable time lying at the surface, 

 especially in late larval life. Ranids, scaphiopodids, and bufonids seldom do 

 so. Bufonids and ranids often feed in the shallows along the edge of the 

 water and scatter widely into the deeper water on disturbance. Scaphio- 

 podids, hylids, and microhylids (at least in Oklahoma) seldom do this. As 

 is well known, young tadpoles are often difficult to distinguish morpholog- 

 ically and I have for several years used such behavior as an aid in recogni- 

 tion. While these methods are not perfect, I have found them to be fairly 

 efficient for provisional naming of tadpoles and then following their develop- 

 ment and metamorphosis till they can be recognized by more usual methods. 



Let me emphasize again that I do not advocate substituting physiological 

 and ecological characteristics or peculiarities of habits and habit patterns for 

 the usual morphological criteria. But we must study the whole organism, 

 including its habits; where morphological characteristics fail us, then we 

 must use the less tangible distinctions as aids in making determinations. 



Summary 



(1) Salientia in Oklahoma tend to be ecologically as well as geographically 

 distributed. Some species are essentially unrestricted ecologically (within 

 the borders of the state); others are quite restricted; still others, partially 

 so. 



(2) Those that are unrestricted geographically are, nevertheless, sometimes 

 restricted ecologically, Rana catesbelana Shaw, R. berlandlerl Baird, and 

 Acrls crepitans Baird being typical examples. 



(3) Those which are ecologically restricted live in grasslands only, wood- 

 lands or savannah only, or in "islands" where one type of community is 

 surrounded by another. Ecologically unrestricted species range geo- 

 graphically more or less indiscriminately through radically tliffcrent 



