Love is in the air at the Small Mammal House at the Smithsonian’s National Zoo this Valentine’s Day weekend. Keepers helped set “the mood” for their animal friends, doling out hand-crafted valentines and heart-shaped treasures unlike anything from any greeting card company or chocolatier.

These holiday treats were all given as a form of “enrichment”—items that make an animal’s environment stimulating or challenging through the use of toys, scents, puzzles, and anything else that might provide novelty.

To provide enrichment, the keepers created heart-shaped treats (some frozen) made of a variety of foods including beet juice (hence the red color), pureed apples, grapes, and bananas. In other instances, they wrapped up some small mammal favorites: meal or wax worms in bright Valentine’s Day decorative paper, allowing the animal to mentally and physically decipher how to get to their goodies.