What better way to celebrate Earth Day than zoo babies?

The Columbus Zoo and Aquarium's cute factor just went up.

Irisa, a 10-year-old tiger, gave birth to three male cubs each weighing 2 1/2 pounds Tuesday morning, bringing the zoo's Amur tiger total to 10. The newborns are being cared for in an incubator at the Animal Health Center, and the zoo isn't sure when visitors will be able to see them. In the meantime, we have these squeal-worthy photos to hold us over.

Happy Earth Day!

Photo Credit: Grahm S. Jones, Columbus Zoo and Aquarium