Friday, 26 September 2014

Of nets and rings

Dungeness Spring 1977
When bird observatories were being established around the coasts of Britain the main reason for their founding was to study bird migration. Collection of this information could have been carried out purely by observing which species, and in what numbers, were passing through an area at any given time. This was fine to a point, but to be able to identify exactly where these birds had come from and where they were going necessitated a different method of recording. These questions were to be answered, in the main, by the science of bird ringing.

Simply put, bird ringing is carried out by trapping a bird and placing a metal ring on one of its legs. These rings have a unique serial number stamped on them, together with an address of where to send the ring if found. The trapping of the bird needs to be done carefully (to minimise stress) and the ring placed on the leg has to be light (as not to hinder flight and normal behaviour). To be able to participate in this study it is necessary to undergo a lengthy training programme. This is essential, as the handling of birds requires sensitivity, responsibility and a thorough knowledge of the topography of a bird.

At DBO ringing is regarded as the most important function of the observatory and as such a great amount of time and effort is spent on it. The nerve centre of the ringing operation is based in the downstairs front room where all the equipment is stored and the birds taken and ringed. (You can always tell a non-ringer quite simply by the term ‘ringed’. They almost always refer to birds as being ‘rung’).

The ringing room reminds me of a cross between a provincial museum and the Steptoe’s front parlour. It is an Aladdin’s cave of bric-a-brac. There is no visible wall space. This is hidden behind cupboards crammed full with equipment, cases of stuffed birds (Shelduck, Pintail, Long-tailed Duck), cabinets of bird skins, cardboard-boxes overflowing with paperwork, chaotic piles of books, ancient scientific instruments, fading posters and old black-and-white framed prints. An old pram gets in the way but is tolerated as it transports a large heavy-duty box in which the binocular telescope is housed. At the far end of the room, in front of the windows, is a wooden shelf. Above this is a line of cord strung between the walls, on which are placed a series of hooks. Laid out on the shelf are the tools of the ringer’s trade – different sized rings (for different sized birds), pliers (for enclosing the rings around the bird’s legs), rulers (for measuring a bird’s wing length), pesola’s (for recording a bird’s weight), callipers (for taking other measurements such as bill and tarsus length) and the obligatory copy of ‘Svennson’s’, the Holy Bible of how to identify, age and sex species. A wooden chest is hidden underneath the shelf and this is stuffed to overflowing with bird bags. These are hand-made bags (fashioned from any old material) with a string-pull opening into which the trapped birds are placed. This is done for the ease of transporting the bird from trap to ringing room, but also because it calms the birds down. These bags, when with bird, are then hung onto the hooks above the shelf. We then start to process the catch. All information gathered is written into a log book and the bird then released back into the wild, through a small opening in the window. The hope is that this bird will be subsequently recovered and such information as its movement and longevity will be learnt. The room at the end of a busy day is full of loose feathers (a body feather or two from the odd bird, no harm done) and a pile of bird bags that now need a good wash – after all, when a bird needs to go… worst of all are the thrushes when they have been gorging on blackberries. Purple bird shit may look whacky, but it stains everything it comes into contact with.

The commonest way to trap the birds is by mist net. These fine-meshed nets are strung out between poles and in the right conditions can appear almost invisible. A bird will fly into the net, drop into a pocket and then become entangled. I consider the most delicate and skilful part of the ringing process is the extraction of birds from these nets. The nets used to be made in Bridport, Dorset but along came the Japanese and produced cheaper, if inferior versions. England 0 Japan 1. Before the invention of the mist net most birds were caught in Heligoland traps. The observatory has several of these and work on the principle of walls of wire-mesh which run along and above a line of bushes, narrowing as they proceed, thus funnelling birds into a dead end where a simple catching box is housed.

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