Turkey Vultures are considered partial migrants, as northern populations migrate, while southern populations generally do not. Vultures that breed in Eastern North American typically travel no farther south than Florida and Texas. Western populations migrate at least as far as Colombia and Venezuela, and some experts believe that some western birds may travel as far south as Brazil and Argentina. I saw a few vultures heading south in ones and twos, while most birds had formed groups of six or more. The largest group that I saw totaled 14 individuals.
When I checked my email this morning, I noticed that the major hawk watch locations along Lake Erie all reported more Turkey Vultures flying south than any other raptor. Holiday Beach recorded 2389 vultures, Hawk Cliff in Port Stanley recorded 3749 vultures, and the Detroit River hawk watch had counted 3660 migrating vultures. The two hawk watches in Whitby – Iroquois and Cranberry Marsh – counted only 212 and 641 respectively. These numbers confirmed my own observation that a large movement of Turkey Vultures had indeed taken place on Thanksgiving Monday.
A few groups of vultures appeared to be circling over the fields rather than gliding south over the 401. While the sight of circling vultures may indicate the presence of an animal carcass, they may also circle to gain altitude for long flights, search for food, or engage in play. A group of vultures is called a “venue”, while vultures circling in the air are a “kettle”.
Turkey Vultures can soar for hours without flapping their wings, making this the most energetically efficient form of travel by far. In fact, soaring vultures use only slightly more energy than they do when standing on the ground doing nothing! Their flapping, when it occurs, appears laborious and is usually used when taking off or landing.
Turkey Vultures usually don’t begin flying until a few hours after sunrise, after the air has been warmed by the sun. They gain altitude on pockets of rising warm air, called thermals, by circling frequently until they reach the top of the thermal. They are then able glide across the sky at speeds up to 100 km/h, while gradually losing altitude. When they need to gain more altitude, they locate another thermal and the process of circling, rising, and then gliding begins again. Turkey vultures can cover many miles going from thermal to thermal without ever needing to flap.
Watching the many Turkey Vultures soaring in the blue October sky – along with the occasional Red-tailed Hawk and Great Blue Heron, and the numerous Red-winged Blackbirds and starlings – helped pass the time on the long drive back to Ottawa. I hope they all reach their destination safely, and look forward to seeing them again in the spring.