An avocet has a long, strongly upcurved bill which contains a complex and highly specialized system of lamellae capable of filtering out small food items.
Plus, an adult's saliva can help predigest the food, making vitamins like B12 easier for the baby to absorb.So, mouth to mouth attachment has a history of intimacy, trust and closeness.
I got this idea from visiting my friend's kindergarten classroom. She would ask her students to kiss their brain, and they would take their fingers, tap them to their mouth and then to the top of their head.