We all know birds have beaks or bills but due they have teeth to chew their food? Are those beaks or bills (used interchangeably) just for eating purposes? The answers to these questions is no! All wild birds’ beaks or bills function in several ways depending on their environment and dietary needs. This article will address land birds such as songbirds, perching birds and birds of prey etc. though water birds and waterfowl follow many of these concepts will be addressed in a future article. Bills or beaks come in a variety of shapes and sizes all defining the function it plays in the wild bird’s needs.
Wild birds beaks consists of two bony structures forming the upper and lower mandibles. These structures are encased in a thin covering of keratin (protein) formed by epidermis cells which grow from plates at the base of the mandibles. This sheath is called rhamphotheca. These cells continuously grow to replace old and worn areas of the bird’s bill. The upper mandible (maxilla) is embedded into the skull. Each side of the skull has a bony prong which attaches to the maxilla. A nasofrontal hinge allows the upper portion of the beak to move up or down. The lower mandible is attached by two plates forming a U-shape or V-shape structure that supports the maxillary bone. The plates attach to either side of the skull. Jaw muscles allow the beak to close though they are weak muscles for the most part.
Most wild birds have tomia on their mandibles. These are rounded, sharp or saw-toothed cutting edges on the mandibles. This structure helps slice though seeds, insects or lizards etc. The tomia aid in holding the prey or a slippery fish from escaping or slipping out of the bill.
Wild birds have a tooth on the beaks as hatchlings to aid in breaking their shell to come into the world. This disappears after hatching. Ducks and swan have bill nails or bill horns on their beaks which are simply layers of keratin that help in digging up plants or opening shellfish.
In some wild birds the bill changes color or varies in brightness to attract a mate. Once the breeding season is over the keratin layer sheds off and a new layer or covering replaces it. Puffins are a good example of this phenomena. The cardinal is a good example of the beak getting more vibrant to attract a mate.
Bill clapping and dancing to attract a mate is seen in wild birds such as cranes and storks. The birds touch their bills and dance in a mating ritual with their heads bobbing and interacting with each other. If the pair stay synchronized the pair stay together, if not they part and look for a different mate. Drumming of the bill is used by woodcocks and grouse to attract and find their mates.
When birding or bird watching notice the type and bill size compared to the bird’s head and body to help in identify the bird sighted. The shape will aid in classifying the type of food the wild bird prefers. The category the wild bird fits into whether it is a seed eater or insect eater is not always cut and dry because at different times of the year or season the birds may cross over in what they eat. For example robins eat mostly worms or grubs in the spring or when rearing their brood but as berries become available they may eat them instead. When the worms become harder to find in the fall or winter months the holly berries will become their prominent food. Hummingbirds and orioles sip large amounts of nectar in the spring but will sup on insects and fruit respectively as the seasons progress.
Basically the beak determines the food the bird prefers and how it gets it. The bill size and shape aids as a tool in achieving the bird’s goals. The following is a basic general list of the various beak shapes and sizes of wild birds and their food preferences.
Seed eaters have conical bills which crush and slice seeds, nuts and pits. The larger heavier looking bills belonging to cardinals and grosbeaks tackle bigger and harder shelled seeds such as sunflower and safflower seeds, maple pods and spruce nuts. The smaller conical beaks of finches, buntings and sparrows crush smaller seed of grass, millet and thistle.
Nectar eaters possess long, thin, slightly downward curved straw like bills which enable the hummingbird to go further into the flower to sip the sugary substance, nectar.
Nectar and fruit eaters tend to have longer and narrower beaks than the seed eaters but shorter than the nectar eating birds. Scarlet tanagers, vireos and orioles peck at the fruit of apple, cherry, berry bushes and trees to obtain their food. The toucan is an exception in bill length with its colorful long bill enabling the bird to reach the avocados and pulling them off the tree.
Insect eaters have thin short pointed beaks that can open their bills wide so they can catch the bugs in flight. Their bills are extremely small compared to their head. Swifts and swallows enjoy their in flight snacks.
Probing bills are longer and more pointed than the insect eaters beaks. The bills appear thicker and heavier in breadth though they are not heavy because most beaks are hollow. Robins, grackles and flickers stab at grubs, larvae and insects in the ground with these pointed bills.
Chiseler beak birds many times overlap with the prober beak birds. They have heavy long bills that can hammer on trunks of trees as well as drilling and chiseling holes. These heavy ever so slightly bills are quite powerful and allows the bird to drill for insects as well as excavate large holes for nesting purposes. The woodpecker family of birds also uses their bills to drum for a mate.
Tearing or ripping beaks are very large heavy looking beaks with a very sharp hook at the end of the beak. These beaks belong to hunting birds of prey. The owl, hawk and eagle family use this hook the pierce its prey killing it. The beak allows the bird to rip or tear the prey into pieces. There is a little tooth on the upper mandible that aligns with a space on the lower mandible to hold the captured in place while the bird is in flight. Vultures are in this group too, although they do not hunt but are opportunistic birds that tear and rip their carrion.
Though wild bird beaks or bills are similar in many ways their functions and dietary needs are dictated by the shape and size of their bills. It is necessary to remember that wild birds do cross over into other categories depending on the availability of food in that season. Bills act as tools whether it be for nest construction, mating or for playing. Jays and crows love to pick up shiny objects and play with them before taking them to its nest. Other birds like to pick up threads, animal hair and materials to weave into their nests or line the nest. No matter what the job is the beak plays a major role in the bird’s life. Knowing the shape of the bill helps to identify a bird sighted by the bird watcher or where the bird watcher may find a certain bird to add to his or her’s life list.