Numerous plastic bags were found in the stomachs of more than half of the 14 wild deer that have died in Nara Park in Nara Prefecture since March, prompting the local government to take action to protect them.

According to the Nara Deer Preservation Foundation, nine deer have died after swallowing plastic bags. Masses of tangled-up plastic litter and packets of snacks were retrieved from their stomachs, with the heaviest amount weighing 4.3 kilograms.

Their habit of eating plastic bags is likely to be linked to the fact that tourists take food from such bags to feed the deer, according to Rie Maruko, a veterinarian who belongs to the animal conservation group.

The deer learn that such bags contain food, or are tempted by the smell coming from the discarded packages, leading them to accidently eat them, Maruko said.

Over 1,000 deer are in the vast park, and tourists are allowed to feed them with digestive and sugar-free crackers for deer, or shika senbei, that are sold in nearby shops.

But some tourists are apparently giving the deer other snacks.

Deer, which usually feed on grass, are ruminants and have a four-chambered stomach. If their first chamber is filled up with objects they can’t digest, they will be unable to discharge them from their bodies.

As a result, these deer may have died from malnutrition and weakened immune systems, among other factors.

“The deer that died were very skinny and I was able to feel their bones,” Maruko said. “Please do not feed them anything other than the designated shika senbei.”

The Nara Prefectural Government plans to investigate the situation and step up efforts to warn visitors not to feed deer anything other than the designated food, such as by putting up signs with illustrations, officials said.

Members of the foundation, meanwhile, regularly patrol the area to protect the deer, which are designated as national treasures, from accidently swallowing discarded plastic bags or any other items that are not safe to consume.

On Wednesday, the foundation and volunteers organized a cleanup campaign to get rid of plastic bags and other trash found in the park.

Participants also picked up litter at Kasuga Grand Shrine and Kofuku Temple nearby.