Animal Diaries Archive
Birds and beaks
25 January 2008
This week we are going to take a look at a very important part of a bird's anatomy; the beak. Like a human nose, beaks come in all different shapes and sizes. There's hooked, curved, thin, snubbed, flat, long and pointed, and like us they couldn't survive without them.
The beak, bill or rostrum is used for eating, grooming, manipulating objects, killing prey, probing for food, defense, courtship and feeding their young.
Beaks can vary significantly in size and shape from species to species. The beak is composed of an upper jaw called the maxilla and a lower jaw called the mandible. The jaw is made of bone which is typically hollow or porous to conserve weight for flying. The outside surface of the beak is covered by a thin horny sheath of keratin called the rhampotheca. Between the hard outer layer and the bone is a vascular layer containing blood vessels and nerve endings.
The beak has two holes called nares (nostrils) which connect to the hollow inner beak and then the respiratory system. The nares are usually located on the upper beak. On some birds the tip of the beak is hard dead tissue used for heavy duty tasks such as cracking nuts or killing prey. On other birds such as ducks the tip of the bill is sensitive and contains nerves for locating things by touch. The beak is worn down by use, so it grows continuously throughout the bird's life.
Some examples of birds whose beaks are used for different purposes:
• Raptors such as hawks, kites, eagles and owls have hooked beaks which are basically their knife and fork and are used to tear the flesh off their prey items.
• Jabirus, brolgas, egrets and herons have sharp pointed beaks which they use to stab their food.
• Ibises have long curved beaks used for probing in the mud for worms, frogs,mollusks etc.
• Honeyeaters have long pointed beaks, ideal for obtaining the nectar from flowers.
• Finches have short broad bills more suited to eating seeds and grains.
• Robins, flycatchers and wrens have short thin beaks more useful for catching insects.
• Parrots have strong broad beaks which are great for cracking nuts and hard seeds.
Next time you are wandering through Australia Zoo, take a closer look at our numerous bird species and you will be able to work out what they eat by the shape of their beaks!