Unless kettling is strictly a fall activity. TVs return to NM in March, usually. I saw my first a few days ago.

Backyard Naturalist: Turkey Vultures’ ‘Kettling’ Prepares Them for Long Trip | Lewis County Outdoors

The very long period of circular “kettling” however, is believed by some to be a period during which the members of each small flock learn to recognize each other and perhaps form a loose bond that will increase their cooperation and feeding success on the heroic flights that may cover 4,000 miles or more.

Backyard Naturalist: Turkey Vultures’ ‘Kettling’ Prepares Them for Long Trip | Lewis County Outdoors