In the same way my dog sheds his coat twice a year, so do these Japanese deer. In the spring they shed their winter coat to get ready for the hot summer, then in the fall they shed their summer coat to get ready for the cold winter. Animals usually live in thick forests and as they walk through the brush the branches and other things they rub against groom out the old hair. But if the animals live in open forests, parks, and fields, like these deer at Nara, you will see patches of the the old hair still clinging to them.