Diel Activity Rhythms in the Hellbender, Cryptobranchus alleganiensis (Caudata: Cryptobranchidae)

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DAILY rhythms of locomotor activity have been found in many animals including salamanders (Ralph, 1957; Bennett and Stanley, 1960; Adler, 1969). We were interested in determining the activity rhythms in hellbenders, Cryptobranchus alleganiensis, to aid in the interpretation of field observations and proposed laboratory work. Field observations indicate that C. alleganiensis is primarily nocturnal (for references see: Nickerson and Mays, 1973). However, there have been reports of diurnal activity at certain times of year, particularly during the breeding season (Smith, 1907; Bishop, 1941). Therefore, we determined the activity rhythm in the laboratory at two times of year, prior to and during the breeding season.