As much as we'd like to think Atka is doing a "happy roll" in honor of spring, he's actually demonstrating a behavior wolves do when something stinks!
When a wolf encounters a new (usually yucky) scent, rolling often ensues. A wolf might begin by lowering his/her head and shoulders, then rub to coat the rest of his/her body and fur with the scent. Scientists have several theories re: why wolves "scent-roll." One theory is that the wolves want to familiarize themselves and the rest of the pack with a particular scent. Another theory is that scent-rolling disguises the wolves' own scent allowing them to more easily sneak up on their pray. There's also a theory is that scent-rolling might make a wolf appear more attractive to other wolves!
Whatever the reason, Atka looks pretty cute doing it!