Beaks and Talons

by Brian Coyle

Aside from feathers, the most distinguishing anatomical characteristics of many avian predatory species are beaks and talons. Beak is a term used most precisely to describe the decurved bill of owls and raptors. Talons are the ferocious weapons protruding from their toes. These two features contribute tremendously to the predatory prowess and often-fierce appearance of these birds.

The development of a bill is one of many adaptations birds have made to improve their survivability. The bill is actually a rigid keratinous sheath called the ramphotheca. It covers both the upper and lower jaws (mandible) and extends forward. In mammals, nails, claws, and hair are composed of keratin. The lightweight bill is far more conducive to flight than a heavy jaw full of teeth. The sharp cutting edges and strength of a beak are highly effective for killing, tearing flesh, and crushing bone. The design is magnificent evolutionary engineering.

Cranial kinesis and the mandibular notch are two fine morphological modifications. Cranial kinesis describes the mobility of the maxilla or upper jaw. The maxilla is not locked in place. The mechanics of the maxilla allow it to slide forward and backward thus enabling the beak to open even wider. The mandibular notch, especially pronounced in falcons, is a feature in raptor beaks that aids in killing prey. It is a sharp notch in the beak that can be slid between a victim's vertebrae to sever the spinal cord.

Talons are impressive claw-like features used to capture, hold, and kill prey. Talons are unique to raptors. Other birds may have similar adaptations but they do not match the combined size and function of raptor talons. The endangered Philippine eagle has talons comparable in size to grizzly bear claws. The power of the feet combined with the piercing design of the talons can easily inflict severe injury even on much larger animals. There are incidents of captured raptors forcing a talon entirely through the gloved palm of a handler or grabbing at a baseball-sized clump of thigh. To the dismay of the unfortunate handler, it may require multiple persons to force open a clenched foot.

Within the raptor classification, vultures are an exception to these features. Vulture beaks are not curved as much as the beaks of other raptors and vulture talons are relatively useless for the purpose of capturing and killing. The talons are not very hooked and the feet are much weaker than other raptors. The feet cannot effectively grasp onto some live prey. Of course, vultures are almost exclusively scavengers, therefore, they do not require the same function from these features.