Building knowledge about the movements of migratory birds is vital if we are to put in place effective conservation measures. Traditionally, in an attempt to understand better migration, birds have been trapped by ornithologists using mist nets and ‘ringed’ or ‘banded’ with small light-weight metal rings. This means that if they are re-trapped by another ornithologist in another location, re-trapped the following year in the same or a different place, or found dead by a member of the public, information can be gained about the migration routes, wintering and breeding grounds and the importance of specific stopover sites. The recovery rate varies but roughly one in a thousand small birds are recovered in this way. In recent years a number of new methods have been used (e.g. wing tags, combinations of coloured leg rings on shorebirds or neck collars on swans and geese), all designed to allow birders in the field to identify individual birds and thus increase the likelihood of a given bird being ‘tracked’.
Looking for colour rings, wing tags or collars adds a new dimension to birding and it is rewarding to see a marked bird, note the colour and letter/number combination, report it to the relevant authority – see here for East Asia and here for Europe – and then receive the “life history” of the bird you saw.
On 15 November at Wild Duck Lake I encountered a Whooper Swan with a neck collar amongst a flock of over 30 swans. The flock consisted of mostly Whoopers but with a few Mutes mixed in (Mute Swans are rare in Beijing and these were my first in the capital). The flock was distant but, with my telescope, I was able to read the number/letter combination on the collar. It was dark blue with white letters/numbers reading “1T86″. I contacted the ringer directly by email and, a few weeks later, I received the following information about this bird:
“1T86″ was captured and marked on 14 July 2012 at Terkhiin Tsagaan Lake (N48° 9’20.98″, E99°40’16.39″), Arkhangai Province, Mongolia. We did not check its sex, but the weight was 9.95 kg at the time of capture.
I put these coordinates into Google Earth and created the map below showing the distance and direction this bird has travelled. Wild Duck Lake was only a stopover site – the swans had moved on when I visited again in December – so I can only guess where this individual is now – very likely somewhere further south where at least some water bodies remain unfrozen.
Data like this helps ornithologists to understand migratory movements and is invaluable in informing conservation planning. So reporting birds like this makes a genuine difference to our collective knowledge of birds and directly supports those trying to conserve our birds. For me, as a mere birder, it also reinforces a sense of wonder at the journeys our birds undertake each spring and autumn and is a reminder that Wild Duck Lake is a vital stopover site for many migratory birds.