A Comparison of Growth and Rattle Strings in Three Species of Rattlesnakes

Abstract

Rattle strings are compared in a large series of Crotalus atrox from five Oklahoma roundups with those of C. viridis from the Sharon Springs, Kansas, roundup, and with a smaller series of C. horridus from the Fitch Natural History Reservation and environs in northeastern Kansas. The 1590 rattlesnakes examined included 153 C. horridus, 426 C. viridis and 1011 C. atrox. Those from the roundups were mostly adults. Adolescents of all three species have tapered rattle strings with the natal "button" at the tip. Adults with more than eight rattle segments rarely retain the button, but may have tapered rattle strings if they still have segments acquired when they were smaller, or they may have parallel-sided strings of uniform sized rattles if all of the segments acquired during growth have been lost. In adult C. horridus just over half of the rattles are same-size segments, in C. viridis the ratio is just over one-third, and in C. atrox not quite one-fourth. Reverse taper, with an occasional undersized segment seemingly caused by undernourishment, was observed in all three species.