Weight in adult females can average some 7 kg (15 lb) while 5 wild-caught males averaged kg ( lb). The porcupine is the only native North American mammal with antibiotics in its skin. Those antibiotics prevent infection when a porcupine falls out of a tree and is stuck with its own quills upon hitting the ground. Adult porcupines can be covered with about 25, quills, which vary in size on different parts of their bodies. "Large quills and more of them make porkies look big and healthy," notes the scientist. Not all porcupine experts, however, believe that visual cues play as important a role as Sweitzer is ascribing to them.