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 fact that oak trees matures slowly symbolically reminds us how great strength and power can be achieved through patience and faith. So, in a nut shell (hehe!) acorns and oak trees symbolize: longevity, humble beginnings, patience, faith, power, endurance, and strength.