Changes in the antlers of Yaku Is Sika Deer
July 19, 2026
When spring arrives, a change occurs in a certain part of the body of the male Yaku Is Sika Deer.
That is... a "horn"!
Only Yaku Is Sika Deer (a subspecies of Sika Deer) have antlers, and every year around the end of March, their fully grown antlers fall off. This is called "antler shedding" and is a phenomenon observed in animals of the deer family.
Currently, Inokashira Park Zoo houses two female and one male deer in its enclosure. This male's antlers fell off on March 23rd of this year (2026)! The timing of antler shedding can vary by about a day between the left and right sides, so it's very lucky if you can see one antler still attached.
When a deer sheds its antlers, there may be a little bleeding at the base of the antlers, but please don't worry. After a few days, the red area will scab over and close up naturally. Shedding antlers is a natural phenomenon for deer, and they don't seem to be bothered by it too much.
After about two weeks, the detached area begins to swell up, and new horns start to grow in preparation for the mating season in the fall.
In May, the horns were forked, but by late June, they had grown about 50 cm and begun to split into three. Horns in the process of growing are called "velvet horns," and their surface is covered with skin. Because velvet horns are filled with blood, they feel slightly warm and a little soft to the touch. Also, if you look closely, you can see fine hairs growing around the horns.
In the autumn (around the end of August to September), once the horns have finished growing, the skin covering the horns loses its blood supply, dries out, and peels off. This is called "horn breakage."
During this time of year, Yaku Is Sika Deer can be seen rubbing their antlers against tree trunks and branches, peeling off the bark that remains around the antlers. As the bark peels away, hard, white antlers are revealed. These are called "branch antlers."
During the mating season, male deer use their antlers to fight each other for females. The male that wins the fight is able to leave behind offspring.
Currently, the deer enclosure houses only one male, so you won't see them using their antlers for fighting, but you can see them sharpening their magnificent antlers.
*There are also male Yaku Is Sika Deer in the large enclosure. Please observe the changes in their antlers as well.
[Inokashira Park Zoo Animal Care and Exhibition Staff, Onodera]