This video says about itself:
A ferocious battle between a Kestrel and a Jackdaw! The Jackdaws previously destroyed the Rock Dove nest in the nest box. But claiming this space won’t be so easy. The Kestrels, who have previously nested here, want to come back.
Today, a group of jackdaws near the church, looking for food.
One of them drove away a jay.
Patterned feathers, previously thought to be used only for camouflage in birds, can play an important role in attracting a mate and fending off rivals, a University of Melbourne study reveals: here.