To celebrate Halloween, here are some photographs of wild animals with glowing eyes that give them a somewhat otherworldly to slightly evil appearance (especially those with red eye shine). Animal eye shine is due to the presence of tapetum lucidum, a special layer behind the retina that reflects light back into it to improve their vision in low light conditions.

Despite its gleaming red eye, this friendly little Desert Cottontail (Sylvilagus audubonii) still manages to look wide-eyed and innocent.

However, a glowing red eye more accurately reflects the devilishly scheming nature of this Rock Squirrel (Spermophilus variegatus) below.

Wickedly clever Rock Squirrels always find a way to steal fruit from trees, vegetables from gardens, food from bird feeders, and eggs from bird nests. Some of the Rock Squirrels in my yard have grown so fat from all of their thieving that they can barely run and can at best achieve a fast waddle.

Unlike the red eye shine of the rabbit and the squirrel above, all of the wild rats and mice I've photographed here in Tucson have had a pale violet eye shine.

I spotted this glowing-eyed Arizona Cotton Rat (Sigmodon arizonae) above at the Sweetwater Wetlands here in Tucson, where they are very common.

Elk (Cervus elaphus) are not found in the Tucson area. To see Elk in Arizona, you have to travel to the northern part of the state.

This Elk with eyes glowing brightly in the camera's flash was munching shrubbery in front of Maswik Lodge in Arizona's Grand Canyon National Park.

Another native deer found here in Arizona is the smaller Mule Deer (Odocoileus hemionus), which is found here in Tucson and throughout the state.

This Mule Deer was still growing his velvety antlers, and his eyes glowed a pale green when lit by the camera's flash. Deer have bright eye shine and it is a good way to spot them in the dark.

I would have never noticed this White-tailed Deer (Odocoileus virginianus) above on the dark lawn of the Southwestern Research Station in Arizona's Chiricahua Mountains if my flashlight hadn't first caught the bright flash of its eyes in the darkness.

For more of my eye shine photos, check out those from last Halloween and those of a frightened dog with green-eye, an angry Great Horned Owl with red-eye, and a brave dog with odd-colored eye shine.