While most deer at the park demand food from visitors, some seem to be more attracted to the chains separating the temple's approach and the lawn.
One afternoon, I visited the temple to see the unusual animal behavior with my own eyes. As I observed about five deer in front of the temple's Honbo building, one of them approached the 40-centimeter-tall chain railing, smelled the iron and began biting it.
I looked around and noticed some other deer were doing the same. Some of them only took a bite, while others kept gnawing on the iron chains for about a minute.
One tourist joked, "Are they suffering from an iron deficiency?" while some foreign travelers asked if they were hungry.
According to the Foundation for the Protection of Deer in Nara Park, in 2003 the organization first noticed the animal's strange behavior. Members found a picture of a deer biting iron chains among pictures the group received from the public for a photograph contest.
"I've been watching it for a long time. I thought the animal was getting some kind of nutrition from the chains," said Todai-ji senior priest Sogen Sagawa, 90, who has been living in the temple since his childhood.
However, out of 1,100 deer in the park, only one group of around 10 deer living near the Nandai-mon gate and the Honbo building are engaged in the practice, regardless of season, their age or sex, according to the deer protection group.
"The deer in the group are probably teaching each other to bite the iron chains. The practice has been passed onto younger generations because it's necessary. We will never know unless we ask the deer," said Sachiko Ikeda, head of the foundation.
A veterinarian belonging to the organization commented, "Deer maintain their nutritional balance by taking in minerals from soil, but it is unlikely that only a certain group of them have an iron deficiency. They may have acquired the habit after biting the chain by accident."
Meanwhile, the chief keeper with city-run Tennoji Zoo in Osaka's Tennoji Ward said, "Cows sometimes take in iron from the nails of their barn, but I'd never heard of such a case among deer. They are probably short of iron or they just enjoy the texture of the chain." (By Shigeto Hanazawa, Nara Bureau)