I like a conversation that begins with, “You’re witnessing one of nature’s weirdest phenomena that we still don’t fully understand.” And that’s exactly what Scott Aker said the other day when I rang him up at the National Arboretum, where he is the head of horticulture and education. …“We’re seeing a lot of white oaks now producing a bumper crop of seeds,” he said. It’s called a mast year. …“It’s called the predator satiation hypothesis,” said Michael Steele, a biology professor at Wilkes University in Pennsylvania. …Every few years, trees such as oaks produce an overabundance of acorns, so many that the predators can’t possibly eat them all.