• Male antlers are shed annually and regrow.
• In captivity deer have lived more than 20 years.

Japanese sika deer typically live from 7 to 20 years, with a maximum recorded lifespan of 26 years and 4 months, and a theoretical lifespan ranging from 13 years and 2 months to 26 years and 4 months. The species reaches sexual maturity from 1 year and 3 months to 4 years of age; the young are born with their eyes open and begin walking immediately. During the embryonic stage, the fetus develops inside the mother and receives nourishment via the placenta, followed by the fawn stage, where the young lives with its mother, hides in grass, and feeds on milk for a duration of from 1 day to 1 year. The adult stage begins at 1 year and 1 month and lasts until 20 years of age, during which time adult deer can reproduce and males grow antlers.