By Sue Curnock
Seeing a sparrowhawk is something really special. These magnificent birds of prey are adapted to hunt smaller birds in confined spaces, twisting between the trees like an arrowhead. They are extremely agile, flying fast and low against vegetation to remain hidden from their target for as long as possible.
There are marked differences between the sexes: Females are 25% bigger and have a grey-brown back with brown barring on their chest, while the male’s plumage is grey-blue with orangey brown barring on the chest and orange-brown cheeks. Both sexes have bright yellow legs and eyes and dark barring across the tail.
Unfortunately sparrowhawks have had a tough time in recent centuries due to persecution from trophy hunters and gamekeepers. Numbers recovered slightly during the 1940s, but crashed again in the 60s and 70s due to the widespread use of pesticides such as DDT. These caused a number of problems including thinning of egg shells which meant females often cracked their own eggs as they tried to incubate them. Their numbers began to recover once these harmful chemicals were banned and there is now a good breeding population in
Some people are concerned that sparrowhawks are causing the decline in some songbirds, but there is really no evidence to support this. In fact, if you do see one it means there must be good numbers of small birds thriving in the area. As a top predator, sparrowhawk numbers are controlled by the availability of their prey, not the other way around.
Smaller birds tend to rear between five and 15 young in a season. Only two need to survive to breed the next year to keep the population stable and in the absence of predators, many of them will die of disease or starvation. On average, only one in ten sparrowhawk hunts is successful; their arrival is heralded by a wave of agitated twittering as smaller birds flee to safety. They prefer to go for sick or injured birds which are much easier to catch. Only birds that are the fittest and best at avoiding capture survive to successfully breed, so natural predators are an important factor in keeping a population healthy.