In this Sept. 11, 2018, photo a squirrel chews acorns in Portland. Credit: Robert F. Bukaty | AP

It’s a boom year for acorns in Maine, where parks and lawns are covered in the squirrel-attracting nuts.

The bumper crop of acorns is the result of a phenomenon that happens every two to five years. The Portland Press Herald reports scientists have struggled to explain why these irregular “mast years” sometimes flood communities with the acorns.

Acorns fall from oak trees, and it’s possible the irregular years of heavy acorn drop are a product of evolution. The Press Herald reports the acorn ebb and flow suppresses populations of rodents and other acorn-eaters during leaner years.

Scientists have also posited that weather conditions might also play a role in the abundance of acorns. For now, Maine’s squirrels certainly aren’t complaining.