Wait to put up outdoor lights on posts, shrubs or small trees until after the peak of the deer rut, sometime after the first week of December.
Trees with trunk diameters of two-to-six inches are most likely to be rubbed by bucks, which entangle lights in their antlers. Use multiple short strands of wire plugged together (versus one long strand), so that if animals become entangled, they will have less cord to deal with.
Avoid stringing lights "clothesline" style across areas, and firmly attach lights to tree limbs, gutters, or fence posts. Place flagging along the wired decorations so that deer can see where the wire is, and avoid entanglement. Disconnect and store water hoses, tomato cages and other garden materials (netting, stakes, ties, etc.) until spring, and take down and store hammocks and swings when not in use.
As to when to intervene, "One of the greatest hazards to an entangled animal can be a well-meaning citizen who comes too close," said Casey Westbrook, district wildlife manager for northeast Elbert County. "People should not approach or try to help an entangled animal. Greater injury to the animal or injury to the person may result. “ Although Colorado Parks and Wildlife is often called to remove objects from wildlife, it is important to understand that capturing and handling animals can be very stressful to them and can result in animal mortality. Because of this, the agency generally does not remove objects from animals unless the object is impeding the animal’s movement, has completely blocked its vision, or is around the animal’s jaw, neck or chest where constriction will affect its survival. However, animals which have become attached to each other because of man-made materials do need assistance, as this kind of entanglement can result in death.
Wildlife officers and biologists are available to assess situations and determine the best course of action; contact a local Colorado Parks and Wildlife office if you believe an animal is at risk because of entanglement. For a list of wildlife offices, go to wildlife.state.co.us/about/officesandphone/pages/contacnumbers.