Hyenas dug right into the leftover trees that were donated by a lot in Alameda.
The Oakland Zoo put the trees in the animals' pens Thursday morning and hid treats inside.
The animals enjoy smelling the pine scents and snapping the twigs while they search for their food.
"Instead of just tossing food into the ground, they will have to put a little more energy into it to get out what they desire," Oakland zookeeper Adam Zuby said.
Meerkats also got the Christmas tree treat.
Other animals at the Oakland Zoo, like elephants, actually eat the trees while squirrel monkeys turn the trees into furniture where they rest and hang out.