Bird Week is a Famicom life simulation game. The player plays as a bird and can either play the normal game or the study game. Both game modes are nearly identical except the study game only allows the player to play through one level. The player must feed butterflies to the baby birds so that they can grow big and eventually leave the nest.
Each level represents a season in the ecosystem of a bird. The game starts out in early spring and progresses through to summer, autumn. After autumn, the game repeats itself by portraying the following spring. Since harmful influences from sentient beings are not simulated in the game play, the forest that the birds live in is presumed to be a nature preserve. If the proper amount of butterflies are not fed to the babies, then the babies end up starving to death. The player will automatically lose a life if any of the baby bird dies. In addition to this, the player also loses a life when a predator catches the player trying to deliver butterflies to his or her baby.