Not all migratory birds are beautiful songbirds, like warblers and orioles, or dynamic shore birds like sandpipers and ducks.
Turkey vultures are migratory birds too. We are just seeing the tail end of the groups that fly through Southern California headed north and east for the summer. The west end of the San Fernando Valley provides numerous stop-over sites for these under appreciated birds as they return from southern wintering grounds as far away as South America.
Though the turkey vulture has a large wingspan–68 - 72 inches–most only weigh between 3-6 lbs. Their light weight body and wide wings enable them to travel great distances without flapping a wing. Turkey vultures can soar great distances riding the thermals in the air currents 3-4,000 feet above the ground. The upturned "V" shape of the wings acts like a kite and it is a clue that the bird you are watching is a turkey vulture and not a hawk. Hawks tend of hold their wings more flat.
While turkey vultures are masterful at soaring, taking off can be a challenge, especially from the ground. (Or if their wings are wet from rain or heavy dew. See video of turkey vulture drying its wings.)
Starting from a lofty position makes taking to the air easier. Migrating turkey vultures look for roosting sites high in trees and/or near areas with rising thermals. They will ride rising warm air by making wide circles gradually increasing their altitude. This is called "kettling." (Some mornings in the fall when the turkey vultures are in larger groups migrating south, the Ventura (405) Freeway grinds to a halt with anxious commuters wondering why 40-50 vultures are circling over the highway.)
For turkey vultures a stand of large trees is an important temporary roost during migration. These birds may not be beautiful in a Western tanager sense, but they are vital components of a healthy environment. Turkey vultures eat the dead and help complete the cycle of life. The site of a turkey vulture overhead is a hopeful sign for a healthy environment.