Reasons for ringing
To be able to follow the individual birds’ movements, and to be able to say who is partnering who, and how many chicks they raise, it was necessary to uniquely mark the individual birds. The only way to do this is to colour ring them.
Apart from the colour rings, each bird also has to have a SAFRING which is registered with the Animal Demographic Unit (ADU) at the University of Cape Town. These rings have a unique number so that if a bird is found dead or injured, or is trapped, the ADU can pass the information on to the ringer about where the bird was found.
The SAFRING web address is: http//safring.adu.org.za
Telephone +27 (0)21 6502421
Also see our “Contact details” to inform us directly of any such findings.
Because there is such a big size difference between the male and female Black Sparrowhawks, we have to use different size rings for the the two sexes. On the left is a ring for a male and on the right is a ring for a female.
Because we have only seven colours it has been quite a challenge to ring all the birds with unique colour combinations. When people observe birds and want to send ring combinations to us there are a number of things that we need to know in order to make an accurate identification:
The colours and which leg they are on. It is also important to note which colour is above the other.
As you can see in the pictures above, the bird on the left is ringed: purple over red on the right leg and SAFRING on the left leg.
The bird on the right has a different combination. It is ringed gold over SAFRING on left leg and blue on the right leg.
The other very useful information is a description of the bird: is it a white or black morph? If it is a black morph, does it have a white throat?
The hardest of all observations to make is, is it big or small? This helps us guess whether the bird is male or female. It has taken the people involved in this project many years to be able see a bird in the distance and to know which sex it is. (You would be surprised at how often we end up arguing about it). But sometimes you may be lucky to see both the male and female together. Or, if you are really lucky, you might see them mating (see the first picture in the section on “Breeding“). Then it is the one on top that is the male.
So in summary: any information at all is useful.
The guidelines for trapping birds are very strict. Not only does the trapper have to have had training in handling and ringing of the birds, but they also have to be registered with the ADU who gives them permission to do so. In addition, they have to have permission from the Province in the form of a “hunting licence” to be allowed to trap.
In our project we are not allowed to harm the birds in any way and they have to go back into the environment in the same condition that they were in when they were caught (except, of course, that they will now be wearing rings on their legs). For us it is a real privilege to be able to handle our birds.
Trapping is a real hassle, a bit like war, hours and hours of boredom with short bursts of excitement. As a result we much prefer ringing the birds as chicks. Not only are they easy to get and handle, but we sometimes get three at a time.
Mark Cowen who is a rock climber joined the team and has turned climbing trees into an art form. Many of the trees that the Black Sparrowhawks prefer to nest in are in forestry plantations, therefore climbers are not allowed to use spikes for climbing the trees because that damages the wood. Mark therefore uses a system of slings to hoist himself up the tree trunk, unless, of course, there are convenient branches to use as a ladder.
Mark also knows how to handle the chicks, which is extremely important. We have a short period when the chicks are between three and four weeks old when we can ring them. At that age they are, if not delicate, easily hurt. Any injury to a hunting bird can be life threatening because of its arduous life style.
Mark, in the picture above, knowing how frightened of heights I am, demonstrated his safety equipment on a low tree to put my mind at rest.
The chicks can be very sweet, but that is not so in every case. As you can see by the chick below (picture on the right) it has decided it doesn’t like this big monster coming up to the nest. Sweet or not they are always entertaining.
One of the interesting things about their nests is that they are very clean. There is never old food lying around, and from when they are tiny chicks, they squirt (defecate) over the edge of the nest. You can see the “white wash” from the squirts on the tree trunk in the the picture on the left.
Once Mark has got to the nest and photographed the chicks he places them in a yellow bag that he lowers to us on the ground. He then makes himself comfortable until we have ringed and measured the chicks and sent them back up to him to be replaced in the nest.
One of thing he found very different to rock climbing is that cliffs do not sway in the wind. In one very high tree he found the movement a bit disconcerting.
Mark can be contacted on +27 (0)793217775
Processing the chicks
One of the questions I am constantly asked is how do we know what size rings to put on the chicks? Well, as you will have seen if you have looked in the identification section, the males are smaller than the females. Young birds do not have equal growth all over their bodies. The most important parts get the most nutrition at the time that they need it. That means that their legs and feet grow faster than the rest of them. They start tearing at their prey with their feet long before they are able to feed themselves. This means that at about 3 weeks of age we can identify male and female chicks and fit them with the appropriate sized rings on their legs. Once they are flying around and working for their living the legs become slimmer and more muscular.
The pictures above show a bird who was ringed as a chick (left) and turned up as a breeding male at a nest (right).
One thing we cannot tell at the time of the ringing of a chick is whether it will grow up to be a white or black morph. So no two chicks of the same sex can ever be fitted with the same colour ring combination.