A SIGHT I often take pleasure in is of magnificent birds of prey twisting in thermals or tearing across woodland clearings in the sky above the reserves.

These birds are one of the signs that the natural environment on these reserves is a healthy one as it is able to support these top predators.

I am frequently questioned about this view, as many people have witnessed these birds killing other birds and animals.

These can include some of the reserve's rarer species, such as song thrushes and skylarks.

To us this is upsetting but to the birds it is only behaving exactly in the way nature intended.

Some people have used this to lay the blame for the local and national decline in the numbers of songbirds we so much love to hear singing on a sunny spring morning, at the feet of these birds of prey.

The culprit usually blamed for the decimation of our songbird population is the sparrowhawk, as this bird's diet mainly consists of small birds.

Back in the early 1960s man nearly completely exterminated sparrowhawks through the use of the pesticide DDT.

However, bird records show that even with the complete removal of this predator in many regions, songbird populations did not increase.

This indicated that sparrowhawks or other birds of prey who at that time were also suffering a similar fate, did not influence the numbers of their prey species.

Since the banning of DDT, many of our birds of prey have been in conservation projects to aid their recovery from the brink of extinction.

During this time many studies have been carried out to investigate the ecology of these birds.

From these studies it was found that it was not so much the birds of prey controlling the numbers of prey but the available numbers of prey controlling the size of the populations of predator birds.

So when you see a sparrowhawk tear across a woodland clearing, remember the prey-predator relationship is one of the most powerful evolutionary forces that fuelled all life on our planet.

So allow this sight to lift your heart as the presence of the predatory birds is one sign that it still may not be too late for man to preserve the natural ecology.

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