Hyenas are animals found in The Sims Castaway Stories.
Basically, a hyena is a dog as found in The Sims 2: Pets or The Sims Pet Stories with an exclusive hyena skin. As such they have the same eight needs: Hunger, Comfort, Bladder, Energy, Fun, Social, Hygiene, and Chew. Also just like dogs they can learn behaviors and tricks, but they cannot get jobs.
Hyenas usually appear on community lots at midnight in packs of three to five. It is possible to adopt a hyena in a similar manner to adopting stray pets in The Sims 2 Pets or The Sims Pet Stories. If a male and female hyena WooHoo, the female will get pregnant and give birth to hyena cubs after three days.
There are five breeds of hyenas. They are simply called Hyena1 to Hyena5 and can be found in the PetBreeds folder of The Sims Castaway Stories.
Hyena1 is the more standard breed, because it doesn't have any distinctive features. Hyena2 is very similar to Hyena1, but has a relatively longer snout. Hyena3 has a distinctive red eye color (most hyena breeds have dark brown eyes). Hyena4 can be recognized by its long ears and its unique black tail. Hyena5 has a distinctive purple eye color and short ears. On both Felicity and Wanmami Island, Hyena1 is the most common breed and Hyena5 the rarest. Also, Hyena2 is quite common on Felicity Island, but very rare on Wanmami Island.
The hyena breed files can be moved or copied from the PetBreeds folder of The Sims Castaway Stories to the PetBreeds folder of The Sims 2 (if the Pets expansion is installed). The same can be done with The Sims Pet Stories. They will appear as large dog breeds in CAS. Even though, in Castaway Stories pets can't be created in CAS.