D. couperi will feed upon members of the genus Lampropeltis and such are rarely found occupying the same micro-habitat.
While Drys do not kill their prey by constriction, they have developed a brutal and effective means to dispatch such by pinning and thrashing their prey into submission and swallowing such alive, though they are quite effective in dispatching their prey prior to dinning. In south Florida, I have witnessed a large D. couperi ambush a moderately sized C. adamanteus and nearly decapitate the crotalid with a single bite and thrust.
Due to the effectiveness of a Drys legendary ability to dispatch prey through sheer biting power and force, it is important to use the proper equipment when feeding them in captivity, as feeding response bites are to be avoided at all costs.
Best regards,
Jeff

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Jeff Snodgres
University of Arkansas
snodgresjeffreys@uams.edu
501.603.1947