December 2012 - The Sparrow-hawk


Female Sparrow-hawk with freshly killed pigeon  Lin's garden, Bawburgh 

The sparrow-hawk is adapted to hunting prey in confined spaces such as dense woodland; gardens are ideal hunting grounds and they quickly learn which gardens have bird feeders and constitute 'sparrow-hawk larders'. Our garden is no exception, and we often see a bundle of feathers where the local sparrow-hawk has plucked its prey prior to carrying it off to feast at leisure. The female bird is larger than the male and can catch pigeon, thrush and starling . The male tends to target smaller prey such as tits, finches and house sparrows. They are not averse to taking carrion, small mammals, and even bats are considered fair game. Although it is emotive to think of these birds killing songbirds, long term research by the British Trust for Ornithology over a 33 year period has proven that the sparrow-hawk has very little impact on the songbird population. In fact, sparrow-hawks remove the most vulnerable individuals, enabling the fittest to survive, hence improving the health and survival of the whole population.

In early spring, if you are lucky, you may see a male performing a 'rollercoaster' flight, climbing up and diving back down to impress a female. They nest in trees, the nest comprising of a flat platform of twigs, with a central cup. Incubation of 3 to 6 eggs is by the female; both adults feed the young. Sparrow-hawks are short-lived, having an average lifespan of only 2 to 3 years. About one third of the adults die each year, deaths peaking in March and April, whilst around two thirds of the fledged young die in the first year, deaths peaking in August and September; the most common cause of death is starvation.

In the 1950s and 1960s, the sparrow-hawk population was decimated due to the use of DDT (organochlorine) pesticides. The DDT caused thinning of the egg shell, hence the eggs could not withstand the weight of the incubating female. Since DDT has been banned, the population has gradually recovered. According to the RSPB, there are now in the region of 40,100 breeding pairs in the UK. Nowadays it is more likely to be loss of habitat or food source that will limit the sparrow-hawk population.

All birds of prey are fully protected under the Wildlife and Countryside Act 1981, making it an offence to kill, injure or take an adult sparrow-hawk, or to take, damage or destroy an active nest or its contents.

lingibson@bawburghvillage.co.uk

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