Parrots are often called hookbills, which is an avicultural term based on the shape of the beak or bill. This distinguishes parrots from softbills and other birds, such as doves and finches. The function of the parrot beak is for climbing, as well as manipulating and crushing objects.
Anatomy & Terminology
The rhamphotheca is the horny covering of the beak. Made up of a hard protein shell of keratin, it covers the bony jaws (the upper-maxilla and lower-mandible). The upper bill is called the rhinotheca, and the lower bill is called the gnathotheca. The cere is the soft, thick portion of the rhinotheca at the base of the upper beak where the nostrils are located. The beak keratin forms from the cere toward the tip at a rate of 1 to 3 mm/month. Continual wear by eating, chewing and rubbing on hard surfaces maintain the normal surface and length of the beak. The tomium is the cutting edge of the beak and the commisure is the corner of the mouth, between the upper and lower beak (Figure 1 & Figure 2 in slideshow).
Parrots are unique in being able to move their upper beak independently and upward in relation to the lower beak. This is because of a unique joint, called the craniofacial hinge (Figure 3 in slideshow), which allows finer dexterity in manipulating objects and increased jaw pressure to crack large, hard nuts. In other birds, the upper beak is fused to the skull and does not move.
Under the keratin covering, the beak has an excellent blood supply and a network of nerve endings, which provide parrots an amazing tactile sensory ability. The most sensitive area is at the tip of the upper beak (Figure 4 in slideshow). The bones of the beak are not solid, but contain air spaces. The nasal and sinus cavities of the head also extend into the beak, and the maxilla contains a portion of the infraorbital sinus.
Page 2