I have not read/heard that about cricket frog coloration. If memory serves me correctly, I mostly find green crepitans throughout the year. I think that the differences in crepitans coloration is just a case of nature not placing all it eggs in one basket. During the drought of last year, green cricket frogs were easy to locate against the brown dying vegetation and I assume that the brown colored cricket frogs were more successful. I don't know the genetics involved with producing brown colored crepitans but I assume that brown parents are more likely to produce brown offspring.