"THE STANDOFF"! Perhaps the Crow is waiting for reinforcements. Two images merged to show the Peregrine perched for some time when the Crow arrived and started squawking. The Peregrine wisely left before the Crow's buddies arrived. The Crow probably knew that the Peregrine's killer weapon is its diving speed when hitting and killing its prey. Being close and at the same level was therefor reasonably safe for the Crow. The Peregrine likely also knew that being harassed by a bunch of animated Crows whilst perched was not a good situation to be in.