Yesterday's high in the Twin Cities was 73, and we reached the mid 60s today, when normally we'd only hit 50. March is going out like a very big, fluffy lamb, and the evidence that spring has arrived is all around: from robins pulling up worms to hardy boys in shorts. Bet you didn't know people study this kind of thing. They're called "phenologists." Jim Gilbert of the Linnaeus Arboretum in St. Peter is a practicing phenologist.