Good question. Daniel Ludwig, IDNR Regional Wildlife Biologist, provided this response:
"Since the occurrence of cougars in Illinois is a relatively new event, the species is not currently listed as a protected species in Illinois. To properly protect the cougar would require Illinois legislation to list the cougar as a protected species under the Wildlife Code, Illinois State Statutes. Since the cougar is not currently listed as protected, the disposition of the animal in Whiteside County was up to the landowner. The landowners requested that IDNR euthanize the animal because of concerns about the landowners' livestock and pets".