Sparrowhawks are one of the most prolific hunting birds with over 120 species of birds having been recorded as sparrowhawk prey. They have also been known to capture small mammals, such as bats in flight.
Female sparrowhawks are usually 25% larger than males, and can tackle birds that weigh up to 500 g including pigeons, starlings, thrushes and magpies. Male sparrowhawks tend to prey on tits, finches, sparrows and buntings. During the summer months about 40% of a sparrowhawk’s diet is fledglings.
Although, it can be distressing to see a sparrowhawk capture a bird or find the remains it has left behind, research has found that there is no obvious decline in the numbers of songbird breeding numbers when sparrowhawks are present and they are no more common when sparrowhawks are not present. In other words, sparrowhawks do not control the populations of their prey, but the amount of prey available determines the number of sparrowhawks in the area.
Sparrowhawks tend to take fledgings or sick, old, injured and weak adult birds, therefore keeping the populations of other species healthy. Birds have evolved to lay many more eggs than is needed to keep a population stable, because so many of their young will die before they reach breeding age.
And what’s keeping the population of sparrowhawks in check? Natural predators include barn owls, tawny owls, goshawks, peregrine falcons, golden eagles, foxes and pine martens.