Fish and Game says don't feed deer

“Despite good intentions, supplemental feeding of deer often harms them, frequently resulting in their death,” Demick said. Although some deer have adapted to live in urban environments and feed on non-native foods, it’s not necessarily a healthy environment for them, he said.

Fish and Game officials receive reports of sick deer in many Idaho cities, especially during the fall and winter, Demick said. “The occurrence of sick deer in towns has been a long-standing issue common among urban deer populations. More often than not, this illness is related to their nutrition,” he said.

Poor nutritional condition in mule deer is caused by disruptions to their digestive system, Demick said. Human introduced foods such as bird seed, alfalfa cubes, deer blocks and livestock feed can disrupt the balance of their stomach microbiome. A mule deer’s digestive system is like other ruminants, consisting of four stomach compartments. Deer are dependent on a healthy balance of bacteria, protozoa and fungi to break down their food. As their diets change throughout the year, so do the gut microbes, slowly adapting to differences in diet composition and forage quality, Demick said.

The change in bacterial composition can take several weeks, making deer poorly adapted to sudden changes in diet. Consequently, even foods with high nutritional value may become difficult or impossible to digest, and animals will often starve to death with full stomachs, he said.

Deer in mountainous habitat of Idaho have a digestive microbiome that is best suited to living off browse, such as shrubs. Some people think that if they supply a different food source, it will prevent animals from damaging their ornamental plants. Unfortunately, supplemental feeding usually encourages wildlife to congregate in higher numbers, resulting in greater damage and problems for people, their pets and the deer.

Feeding a few deer can very quickly lead to many more looking for handouts, concentrating unnaturally high numbers in small areas, which increases the chances of diseases and parasites spreading among the population, according to Demick.

Feeding deer can also attract predatory animals that homeowners and their household pets don’t want around. Mountain lions are common in the forests of Idaho and are sometimes attracted to cities’ confines where deer and elk congregate when fed, he said.