Deerling changes its appearance depending on the current Season. However, this change in form does not occur after capture, unless it is present in the player's party at the time of a season change. This applies to Eggs as well.
When the month is January, May, or September, the season is Spring, and it becomes Spring Form.
When the month is February, June, or October, the season is Summer, and it becomes Summer Form.
When the month is March, July, or November, the season is Autumn, and it becomes Autumn Form.
When the month is April, August, or December, the season is Winter, and it becomes Winter Form.
From Generation VI onwards, seasons are no longer a mechanic in the game, and only the Spring Form has been obtainable in the wild. However, its other forms are retained upon transferring from Generation V and can be passed down via breeding.
Deerling is a Pokémon that resembles a deer fawn. The upper side of its body is pink in the spring, green in the summer, orange in the autumn, and brown in the winter.
Deerling has a yellow-patterned rim, and its underside is peach. It sports a yellow floral tuft on its head, and similar yellow coloration on the insides of its tapering ears. The tips of its limbs are colored black and its pink tail is small. It can change in appearance with the changing of the seasons. If it senses animosity, it hides in tall grass. It moves in herds as it is timid around humans. It dwells in sparsely populated areas, away from humans. It is herbivorous.
Deerling's Autumn Form has, to date, only ever been released as a Pokémon card once; because this card was never released outside of Japan, Autumn Form Deerling has never appeared in the International Pokémon Trading Card Game.
No other Pokémon has the same typecombination as Deerling and its evolved form.
The colors of its four different seasonal forms may be visual references to the colors of trees and bushes during the four seasons: with pink representing blossoms in the spring, green representing fully grown leaves in the summer, orange representing the changing leaves in the autumn, and brown representing the bare, leafless tree and bush branches in the winter.
Deerling may be a combination of deer and darling or yearling (young animal between the age of one to two years old) with -ling being a common suffix to denote something that is small or immature.
Shikijika may be a combination of 四季 shiki (four seasons) and 鹿 shika (deer).