Naturalists are forever looking for the One True Indicator that a season has actually begun, and when it comes to spring, there are lots of signs—and lots of debate about which harbinger is the best. In these days of global climate change, it's a truly hard, even impossible, call. Of course, spring arrives by the calendar in the early 20s of March, but spring conditions visited us in late February, only to be buried in snow and frozen in the cold. At the end of this month, conditions look a tad more reliably vernal, and on this wonderfully warm early afternoon, I spotted the first Mourning Cloak of the season. When these exquisite butterflies emerge from hiding under tree bark—they spend the cold seasons in hibernation as fully formed adults—they're ready to roll and find nectar and mates. When I spot the first Mourning Cloak drinking in the sunshine, I'm traditionally inclined to feel that spring is truly, truly here, and I can safely put away the skis, snowshoes, shovels, and long underwear. This year, the longer-range forecast would suggest that I'd better hedge my bets.