Carrion Crow - Corvus corone

Carrion Crow - Corvus corone

Observation - Carrion Crow - Corvus corone - UK and Ireland. Description: Approx 100 crows and jackdaw all together forming a tunnel type tornado, and swirling around together. What could they be doing?

Approx 100 crows and jackdaw all together forming a tunnel type tornado, and swirling around together.
What could they be doing?