Wednesday, October 27, 2010

Birds and berries

Common smilax (Smilax aspera)
Plants produce berries to entice birds to eat their seeds. 

In most cases the seeds are swallowed whole and after passing through the bird’s digestive system they are deposited away from the parent plant ready to germinate. This sometimes takes place hundreds of kilometres away from their origin.

These plants and birds have developed a vital partnership on which both are dependent for their survival. 

Most berries become ripe at the end of summer or the beginning of autumn, when birds are building the fat reserves that they will be using to provide them with the energy required to migrate to warmer parts of the world. It is also the time when another food, the insects, start to decrease.

Some plants provide berries during the winter and provide food to non-migratory birds even in countries further north where the ground is often covered in snow or frozen making it impossible for birds to find molluscs, insects and other small creatures to feed on.

To ensure that the berries are eaten plants fill them with important vitamins and energy and colour them red or black to make it easier for birds to see them.

 Red berries are usually found in evergreen trees. Trees which loose their leaves in the autumn usually have black berries because these show better against the yellow or brown autumn leaves.

Several species of berry producing plants can be found in the Maltese countryside. 

The most visible is the hawthorn (żagħrun) which produces fruit that look like small apples.

 Less easily seen are the berries of the common smilax (pajżana) which I photographed last Sunday. At this time of the year two other native trees, the lentisk (deru) and the Mediterranean buckthorn (alaternu) have berries.

 These berries are eaten by native species such as the Sardinian warbler (bufula sewda) and migratory species such as the song thrush (malvizz) but unfortunately most of these are shot before they get a chance to eat any berries.

This article was published in The Times on 27.10.2010

No comments:

Post a Comment