These Tree Swallows are hurriedly heading to the south as freezing temperatures take away their prey. Aerial insectivores really have to keep it moving and find sheltered spots that can maintain an insect population despite frigid weather conditions if they are not on the immediate coast or at large bodies of water. We still have some time before it becomes a real problem, but flocks of hundreds of birds had better keep on migrating. It certainly isn’t getting any easier.
