THE AMPHIBIA OF OKLAHOMA 



followed by five during which only a very few young toads were produced. 

 Because of this, we are more sure that the small toads taken in the springs 

 of 1942 and 1943 were produced in 1941 than we would otherwise be. It is 

 evident that a small toad collected in this region in either 1942 or 1943 must 

 have been of the 1941 reproductive period or be a stunted adult, at least three 

 years old (i.e., metamorphosed in 1938 or before). For similar reasons, it is 

 clear that all small to mediuni sized toads collected in the summer and fall 

 of 1941 were wholly or largely products of the 1941 breeding period, having 

 emerged in May or early June of that year. In case of any doubt, the imma- 

 turity of the males as shown by their beginning development of secondary 

 sex charactertistics could be relied upon to validate the data for this sex. 



It seems wise to call attention to differences in behavior of these toads 

 at different ages. Adults emerge in March or April (depending upon tempera- 

 ture) and feed till the coming of hot, dry weather, usually in late June. There- 

 after, old females may be out but males usually are not. Often in September, 

 even after rains, no adult toads of this species can be found in areas where 

 fifty or more can be seen in a half-hour's search earlier in the year. This does 

 not usually apply to juveniles. On emergence at metamorphosis the young 

 toads remain about the pool for some weeks or until all water evaporates if 

 this happens quickly. Eventually, they wander away but apparently do not 

 scatter widely, but seek areas of soft soil in which to burrow. In central Okla- 

 homa this usually means agricultural areas, such as corn and cotton fields, 

 from which they come forth in large numbers at night to feed in adjacent 

 roads and fields and to which they return each morning. Their movements 

 are stimulated by any showers which may come but most individuals con- 

 tinue to feed each night through the summer and well into September 

 whether it rains or not. We have collected young B. cognatus in nights be- 

 tween days of maximum temperatures of over 100°F. when the night tem- 

 peratures were above 90 °F. and when no precipitation had occurred for over 

 a month. 



Commonly in spring and occasionally in fall, rainfall in central Okla- 

 homa is followed by a marked drop in temperature. It has been noted 

 consistently through the years that even heavy rainfall fails to stimulate emer- 

 gence of either B. cognatus or B. w. woodhousii if it is to be followed by 

 such a cold wave. Many times we have failed to find a single toad in several 

 hours' search after rain at temperatures high enough for one to expect them 

 to be out. Invariably, when this has been the case, a severe cold wave has 

 moved in before morning. A possibly related phenomenon is the fact that 

 toads of all ages above two months are active almost in direct proportion 

 to the numbers of insects which are attracted to light at night. It seems that 

 B. cognatus is in nice adjustment to the conditions which will protect indi- 

 viduals from cold and insure an adequate supply of food. The physiological 

 mechanism involved is wholly unknown. 



Collecting areas (all about Norman, Oklahoma), were as follows (see 



Fig-l): 



A. A ditch between a roadway and the tracks of an intcrurban railway, 1.8 



50 



