Bird Droppings

You can learn a lot about birds from simple observation – sometimes the bird does not even have to be present. A posting by Judith referred to piles of bird droppings on the moors above Glossop. The droppings consisted of twenty and above, cylindrical shapes about 25 to 35 mm long. Each cylinder was in two sections: a large mustard coloured section and white section of about 2-3 mm. The mustard coloured section looked as if it contained fibrous matter, and the white section looked similar to white emulsion paint.

Discussion suggested that the nature of the droppings reveals that the bird’s diet is not nutritious and that each bird has to eat a large amount in order to obtain some nourishment. This, if right, would explain the large number of droppings in each pile. Judith commented “The poor birds must spend all their waking hours eating”.

The birds in question were almost certainly Willow Ptarmigan which are plant eaters. They eat shoots, seeds and flowers of heather which are readily available on moor-lands. These foods contain cellulose which is highly desirable as a foodstuff because it is a pure carbohydrate made up of molecules of sugar joined together. It can provide energy when it is digested but the process requires special enzymes and is rather slow. For birds to provide enough energy to support their high metabolic rate they need a gut capable of holding quite a lot of cellulose.

It appears that the Grouse (to use the more well known name) is probably the smallest bird which has a large enough gut to live entirely on plant leaves and shoots. For an Ostrich, with a large body and a low metabolic rate, life as a vegetarian is easy.

Other plant eaters which live mainly on grass and water plants are the Waterfowl like Swans, Geese and Ducks. All are large bodied birds and they all spend a long time eating.

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