Numbers are high in Scotland, yet the sparrowhawk is still a rare sight

Published on Sunday 10 October 2010 17:35

The sparrowhawk is the low-flying jet fighter of the bird world; watch him go at breakneck speed only feet above the ground, up and over a hedge, quickly back down to ground level again and then veer tightly around a bush to flush out a young greenfinch.

Quick as a flash, the hawk makes a tight turn and plucks the surprised finch out of the air. On go the airbrakes and the hawk alights on a fence post, his trophy firmly pinned down in his yellow talons. While he pants slightly from his exertions, the mission has been completed, but for every successful sortie there are many more that finish empty-handed.

Considering it is one of our more common birds of prey, the sparrowhawk is surprisingly unobtrusive and I always think it's noteworthy to see one. Even then, a sighting is often no more than a streak of grey as it flashes low over a road, but sometimes it can be seen soaring high in the afternoon sky.

The sparrowhawk generally favours the lower-lying parts of Scotland, where a mix of farmland, woodland and hedgerow provides a plentiful supply of songbirds - its principal food.

The male hawk is significantly smaller than the female and will typically take birds such as tits, finches and even blackbirds and thrushes, while the female is capable of bringing down larger prey, up to woodpigeon size. While there is a considerable degree of dietary overlap, this difference in size probably helps to reduce competition between the sexes for food, thus making the best use of resources within a breeding territory. The male often favours woodland for hunting, the female tending to exploit more open habitats.

Although the sparrowhawk is a specialist at tracking down its prey in the air, it is generally not agile enough to catch swallows and house martens, and it is not unusual in summer to see these small birds dive-bombing and mobbing a soaring hawk in a bid to drive the unwelcome intruder away.

A pile of plucked pigeon feathers lying on the ground is a sure sign that you are walking through sparrowhawk territory. Surprise is a favoured hunting technique and many a homeowner will have witnessed the "fast'n'low" attack strategy on their garden bird table. This can, understandably, lead to the concern that sparrowhawks are having a detrimental effect on the populations of our cherished songbirds.

The organisation SongBird Survival, for example, believes that there must be sensitive control of selective predator populations - including the sparrowhawk - to aid the recovery of songbirds while habitat improvements take place.

However, most studies suggest that sparrowhawks have no impact on songbird populations. The sparrowhawk is, after all, an essential part of the food web and its population will wax and wane in line with the availability of food, keeping a natural balance as happens in most predator/prey relationships. Small birds can rear many young in a breeding season and logic dictates that for much of the year, sparrowhawks are simply cropping surplus birds that would die anyway through starvation and disease.

In my view, these are all compelling arguments in favour of the sparrowhawk. It seems implausible that there are enough sparrowhawks around to have any overall impact on songbirds. For the songbird species that have declined, landuse and other environmental changes are by far the most likely causes.

It is, nonetheless, an intriguing debate and one that will run and run. Nature is red in tooth and claw, and thanks to the nature of its prey, the sparrowhawk is at the centre of real controversy. But what else would you expect from a bird that lives life in the fast lane?

• This article was first published in The Scotsman on October 09, 2010