Early catkins
One of the most reliable signs of spring is the lengthening and opening of a special kind of tree flower known as a catkin. The term, I'm told, is an Englishism of katteken, which, in Old Dutch, means "kitten"—a reference to the catkin's resemblance to a kitten's tail. Many different kinds of trees and shrubs, including birches, willows—pussy willows are perhaps the best known—oaks, hazelnuts, and alders, to name a few, form catkins, and these typically consist of lots of inconspicuous blossoms packed together. These structures are essentially baseball gloves designed to catch pollen grains borne by the spring breezes, and while catkins will sometimes attract insect pollinators, they offer bees, flies, and other insects scant nectar rewards, so bugs are not all that important in creating the next generation of katteken makers. The catkin crew is primarily interested in what's blowin' in the wind. That's the answer they're after.