There’s still a practise to keep food (what you eat for lunch) for the Crow first, call them “ka ka ka” (or rather invite them) to eat their food before you start your lunch. This is prevalent in many homes even now in this side of the world.
Normally “Crows” are portrayed as the vehicles of Lord Saneeswaran & the link between offering food and appeasing Saneeswaran should be a possibility on why we offer food before we have a feast / lunch.
Anyways, its a good practice to offer food for the winged friends of us. An offering seen at Vengeeswarar temple.