Yes, cats can eat Christmas trees. While cats may find the sight of a tree covered in decorations and ornaments tempting to nibble on, it is not recommended to let them eat the tree itself. Cats can become sick from eating pine needles or the sap from the tree, which can cause vomiting, diarrhea, and other health problems. It is best to keep the tree out of reach of cats and to monitor their behavior when they are around it. If a cat does eat some of the tree, it is important to watch for signs of illness and to seek veterinary care if necessary.