Why do we ring birds?
Much has been discovered about birds by watching and counting them, but such methods rarely allow birds to be identified as individuals. This is essential if we are to learn about how long they live and when and where they move, questions that are vital for bird conservation. Placing a lightweight, uniquely numbered, metal ring around a bird's leg, provides a reliable and harmless method of identifying birds as individuals. Each ring also bears an address so that anyone finding a ringed bird can help by reporting its whereabouts and fate. Some ringing projects also use colour rings to allow individual birds to be identified in the field.
After over a hundred years of bird ringing in Britain and Ireland, we are continuing to discover new facts about migration routes and wintering areas. However, the main focus of the Ringing Scheme today is the monitoring of bird populations. Ringing allows us to study how many young birds leave the nest and survive to become adults as well as how many adults survive the stresses of breeding, migration and severe weather. Changes in survival rates and other aspects of birds' biology help us to understand the causes of population declines. Such information is so important for conservation that the BTO runs two special projects to collect it:
- The Constant Effort Sites (CES) scheme provides information on population size, breeding success and survival of bird species living in scrub and wetland habitats. Ringers work at over 130 CES sites each year.
- The Retrapping Adults for Survival (RAS) project gathers survival data for a wide range of species, particularly those of current conservation concern.
Ringing has allowed us to show that declines in the number of Sedge Warblers breeding in Britain and Ireland was linked to lower levels of rainfall in their African wintering quarters. We have also found that the recent dramatic decline in the numbers of Song Thrushes has been caused by a reduction in the survival rate of young birds. This information will help us to identify the environmental factors responsible for the decline.
Ringing in Britain and Ireland
The British and Irish Ringing Scheme is organised by the British Trust for Ornithology (BTO). Around a million birds are ringed in Britain and Ireland each year by just over 2,000 trained ringers, most of whom are volunteers. On average, fewer than one out of every fifty birds ringed is subsequently reported to the BTO from a different place, so every report of a ringed bird is of value. You can learn more about bird ringing from the BTO publication Bird Ringing: A concise guide, available onlin from the BTO shop.
Part of the BTO Ringing Scheme is funded by a partnership of the BTO, the Joint Nature Conservation Committee (on behalf of English Nature, Scottish Natural Heritage and Natural Resources Wales, and also on behalf of the Environment and Heritage Service in Northern Ireland). The Scheme also receives support from the National Parks and Wildlife Service in Ireland. The volunteer ringers give freely of their time and expertise and also provide a substantial part of the Scheme's funding.
Does ringing affect the birds?
The simple answer is no. It is essential that birds are not affected unduly by the fitting and wearing of a ring; if they were, ringing would not tell us how normal birds behaved. Many studies have shown that birds ringed during the breeding season quickly return to incubating eggs, or feeding chicks, once they are released, and long distance migrants continue to travel thousands of miles between breeding and wintering grounds. Birds will not be affected as long as ringing is carried out by skilled ringers with the utmost consideration for the birds' welfare. It is not surprising that ringing has little effect on birds because, relative to the bird's weight, a ring is similar to a wristwatch on a human.
How are birds caught for ringing?
Birds are caught for ringing in a variety of ways. About twenty percent are ringed as chicks in the nest; this is valuable because their precise age and origin are then known. The method most frequently used to catch fully-grown birds is the mist-net; a fine net erected between poles and is designed to trap birds in flight. This method is very effective but birds can only be removed safely from mist-nets by experienced ringers, who have received special training.
Learning to ring
The skills needed to become a ringer can only be learnt by practice under the close supervision of experienced ringers. Essential skills include the safe and efficient trapping and handling of birds, identification, assessing the bird's age and sex, measuring, record keeping and reporting to the Ringing Unit. For this reason, ringers undertake a several years of training during which they are only allowed to ring birds under supervision. Their progress through the permit system is assessed by an independent ringer, whose own ability has been judged to a high standard. In this way, the BTO Ringing Scheme maintains very high standards of bird welfare and scientific data. A BTO ringing permit is also a legal requirement and has to be renewed annually. If you would like to find out more about how to become a ringer there is more information on the BTO website.