Black Sparrowhawks are medium sized raptors about 55 – 60 cm in length weighing up to 1 kilogram. They are tree nesters and secretive by nature.
The birds’ backs and most of their heads are always black, but their throats, chests and bellies can be almost entirely white or almost entirely black. The black variety can have white throats and/or white flecks on their breasts and bellies. In the white form their waistcoats can join in the middle. These two different forms of colouring are officially referred to as black and white “morphs”, respectively.
On the Cape Peninsula the black morph (picture on the right) is more numerous than the white morph (picture on the left). In the highlands of Africa the white morphs are more common than the black morphs.
Hawks show the biggest reverse size sexual dimorphism of all the raptors. This means that the males are considerably smaller than the females. The Black Sparrowhawk males usually have a mass of about 570 grams whereas the females can have a mass of about 1000 grams.
The picture above shows a male chick, with a mass of 550 g, on the left and a female chick, with a mass of 785 g, on the right. The male chick is slightly more developed than the female but even so the female is much bigger than her brother.
For the first year of their lives the young birds sport juvenile plumage. They are usually red fronted with black streaks, but the plumage can be pale or even mole brown with black streaks. In the picture on the right the soon-to-fledge bird has a full crop so his baby fluff is being pushed out from under his feathers. This shows as a white patch on his upper chest.
Age and eye colour
One of the few ways of judging the age of a Black Sparrowhawk is the colour of the eye. In a juvenile the eye appears yellow (top left). By the end of the first year when it is becoming and adult, it is an orange brown (top right) which then slowly progresses into a dark red colour (bottom left to right).
As mentioned in the introduction, Black Sparrowhawks are forest birds. To cope with flying amongst the trees they have relatively short, rounded wings and long tails. Compare the picture of a buzzard in flight (top) to that of a Black Sparrowhawk (bottom). Buzzards spend most of their time in open habitats and don’t need to be able to negotiate tight flight paths.
If you look at the pictures of the Black Sparrowhawk and the Buzzard above you should be able to see the difference between the lengths of the legs and toes of the two birds.
They hunt different animals and so their hunting equipment needs to be different.
Buzzards hunt mice, lizards, snakes and insects while the Black Sparrowhawks hunt birds. To be effective hunters Black Sparrowhawks need very long toes and talons because this is the only equipment they have for killing their prey. Birds have larger circumferences than equivalent sized mice, lizards etc.
There are other adaptations for hunting birds: Peregrine Falcons have a killing notch in their beaks for breaking the necks of their prey but hawks do not have this.
Black Sparrowhawks hunt birds and their prey of choice is doves and pigeons but females can take birds up to the size of Guinea Fowl.
Picture of Guinea Fowl on the right by Heather Howell.