Cutting up a tree today and caught a huge kettle of migrating raptors. By the time I grabbed my camera they had hit an updraft and were gone . Must have been hundreds...
Q: What makes a group of hawks a “kettle?” — Clair Van Buren, Bloomington, Indiana
A: Hawks and other raptors migrate during the day. As the sun heats the ground, warm air rises from the earth. Certain geographic features, including natural topography or human-built areas, can vary the rate and location of heating, creating columns of warm, ascending air. Birds can enter these updrafts, and by flying or soaring in a circle within the column, they can be lifted high into the sky. As the birds reach a height where the column dissipates because it meets increasingly cooler air, they can simply set their wings and glide down into another thermal in the direction they are headed. Using this method, the birds can travel quite far while conserving energy, as it takes far less effort than constant flapping.