Commentary from source: 當然,剛剛飼養小饅頭的時候,小饅頭可能因為不適應新環境而在籠中滾動,為防止小饅頭的騷動影響到您的正常生活,可以將它們懸掛起來,以免到處滾動
The koyukkuri could roll in the cage as they haven't adapted to the new environment when newly raised. To avoid being disturbed by them rolling around, you can hang them up.