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Bird Ringing

Most peoples' response when I say one of my hobbies is 'bird ringing' is either a blank look or a comment along the lines of 'you mean like, 'Hello Mr Owl?'. Or worse, I've had a few people think I meant 'wringing' birds, which to my mind would make a very unpleasant past-time!

Bird ringing is, in a nutshell, catching birds and putting a uniquely numbered metal ring on their leg so that they can be individually identified, but of course it's slightly more complicated than that.

A typical morning's ringing sees me up before dawn to set the nets. The nets we use are very fine, and not easy to see by either ourselves or the birds. They're set up vertically, strung between two poles which are then 'guyed' to something solid such as a convenient tree, a peg, or a large clump of brambles (which always makes things interesting!). I then leave the net(s) alone for a short time, just enough to allow the birds to start flying about and hopefully into the net whilst I'm gone.

New Hall orchard is an interesting site, because although the number of birds I catch isn't high, the quality of the catch is, so I never know quite what to expect when I go back to the nets. Regardless of the species, birds are extracted carefully and taken back to the 'ringing station' for processing. Here they are identified and fitted with a uniquely numbered metal ring (which also has a postal address for if the ring is found), and aged and sexed if possible. This requires a good knowledge of plumage; some species only differ in the slightest of ways, such as the chiffchaff and willow warbler, the first of which has an emargination (a notch) on the sixth primary feather, whilst the latter doesn't. For some species, there is no plumage differences between the sexes (like the blue tit), whereas others have distinct differences (house sparrow). Some birds have no plumage difference between first year and older birds because they go through a complete post-juvenile moult, but this is unusual. Birds can also be aged by looking at eye colour, beak colour and leg colour.

Once this has all been ascertained, I look at the condition of the bird. Is it in moult? Has it lost any of its feathers for another reason (e.g. a predator)? Does it have reserves of fat for migration? What are its muscles like? A general indicator of health is that of weight, so this is measured and recorded in every case, along with wing length, which gives us an idea of variability in the population. Once I'm happy that the bird has been accurately recorded, and every possible data taken, the bird is released.

With a uniquely-numbered ring on its leg, if this bird is caught again by anyone, anywhere in the world, or if it is found dead, or even if just the ring is found, they are informed who ringed it and where, and what condition it was in. I also get to know who found it and where, in what condition. All the data from all the ringing in the UK is on a central database, organised and run by the British Trust for Ornithology (BTO). They organise and co-ordinate the licenses for ringers across the country, as well as sell all the equipment.

New Hall is my first lone ringing site, and is a successful one too. I've caught a lot of interesting birds, including Mistle Thrush and Green Woodpecker, which I've never seen in the hand before (despite 2½ years of training). To have such an oasis of wild in the centre of Cambridge is an amazing thing and, I think, wholly underestimated. Many thanks to the gardeners who keep it this way!

If anyone is interested in learning more about the ringing scheme, or would like to see some ringing in practise, please don't hesitate to contact me (ess38@cam.ac.uk) to find out more.

Emily Scragg, 2nd Year