My cat does this as well when a bird is close by.....they think they are going native with the lingo. Unless he is taking a course on the internet while I am out, my bird is just pretending to speak beak talk.
acorn - fruit of the oak tree: a smooth thin-walled nut in a woody cup-shaped base. acorn cup, cupule - cup-shaped structure of hardened bracts at the base of an acorn. oak tree, oak - a deciduous tree of the genus Quercus; has acorns and lobed leaves; great oaks grow from little acorns. fruit - the ripened reproductive body of a seed plant.
The fruits of oak (acorns), hickory and walnut trees (nuts) are commonly referred to as hard mast. Hard mast, and acorns in particular (Figure 2), are used by many species of birds and mammals, including white-tailed deer, wild turkeys, squirrels and wood ducks (Figure 3).