Caged birds, such as budgerigars, are often given cuttlebone (the internal buoyant shell found in cuttlefish) for grooming their beaks. By using these ‘whetstones’, so to speak, birds can keep their beaks in shape and prevent that they become too long. Birds in the wild have plenty of opportunities to groom their beaks, but occasionally there are some that do not succeed. When nature goes haywire, the upper or lower beak – or even the entire beak – may become crooked and too long. That makes it very difficult for the hapless birds to ingest food. Ultimately the deformity poses a problem when it comes to building a nest for reproduction and feeding the offspring – if the affected bird actually finds a mate.

Bird Beaks
This Black-throated Canary’s lower beak is double the normal length and the upper beak is very wide on the right-hand side. It is hard to believe that the bird was able to pick up grains and peel them with this beak before swallowing them.

Birds also use their beaks for grooming, an important part of which is spreading an oily secretion from the preen gland through the plumage. This may not be very effective with a deformed beak and as a result the bird’s hygiene will suffer, which in turn will cause diseases and even death.

The slightly smaller lower beak usually fits into the upper beak. This means that by opening and closing the beak it is automatically polished on the edges and retains its optimal shape. Feeding and cleaning, for example on twigs and branches, also contributes to whetting the beak.

For various reasons, however, it can happen that the upper and/or lower beak grows longer and/or crooked and is no longer kept in shape by normal wear and tear. Instead, abnormal growth impedes food intake and can therefore cause the death of the bird.

Beak deformities are caused by a variety of factors: mould toxins may be the reason, or a deficiency of calcium, folic acid, manganese or biotin. Defects during incubation or a beak injury as a chick may also cause abnormal growth in beaks. Other causes, according to scientists, are pollution as well as certain viruses and bacteria. Well-known veterinarian and animal catcher Dr Hans-Otto Reuter says that deformities may also have genetic causes and are hereditary. In the wild, however, it is rather unlikely that a genetic defect is passed on because affected birds usually do not survive long enough for mating.

Bird Beak
The lower beak of this young male Red-headed Finch was unusually high and bent inward, while the upper beak was slightly longer than normal.

In recent years I have seen abnormal beaks almost exclusively in seed eating birds. Once I found a Monteiro’s Hornbill with a cross beak in a nesting box. So far, I have never spotted a bird of prey or an insect eating bird with a deformed beak.

Author: Dirk Heinrich

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