Ringing provides much vauable information on bird movements and survival (click here for details). It is important that the ring is as small and as comfortable as possible for the bird to carry. Consequently rings are made in 16 different sizes to ensure a good fit for all species. Smaller rings (sizes A to C) are made out of a lightweight Magnesium-Aluminium alloy. Rings for species which are longer-lived, or which live in coastal/marine environments are made of tougher 'Incoloy' (a Nickel-Chromium alloy which is resistant to corrosion) or, for the larger sizes (J to L), stainless steel.
The weight of the ring (roughly equivalent to carrying a mobile phone) needs to be compared with the natural variation in a bird's weight, which may be as much as 2 grammes (18%) in a single day for a small bird such as Blue Tit; for the Blue Tit an egg weighs the equivalent of 22 rings.
Ring Size Diameter Weight Typical Species AA - 2.0 mm 0.04 g Wren, Goldcrest A - 2.3 mm 0.05 g Blue Tit, Robin SO - 2.5+mm 0.06 g Swift, Kingfisher B - 2.8 mm 0.07 g Greenfinch, House Sparrow B+ - 3.3 mm 0.17 g Corn Bunting CC - 3.5 mm 0.09 g Song Thrush C - 4.3 mm 0.14 g Blackbird, Starling D - 5.25mm 0.59 g Jay, Lapwing E - 7.0 mm 0.78 g Kestrel, Magpie F - 9.0 mm 1.24 g Woodpigeon G - 11.0 mm 2.40 g Mallard H - 12.5 mm 2.59 g Raven J - 14.0 mm 4.47 g Heron K - 16.0 mm 5.05 g Gannet L - 19.0 mm 5.91 g Greylag Goose M - 26.0 mm 4.31 g Mute Swan
If you find a dead bird with a ring on it, please report it at www.ring.ac
In addition to a measure of size, biometrics can be useful in determining the condition of individuals.
Maximum flattened chord measured on live birds, this measurement will be greater than that of the natural, resting wing, or of measurements taken from museum skins (see Svensson (1992) for details). For each age and sex class for which sufficient data are available (>20 measurements) we give the mean ± 1 standard deviation, together with an indication of the range encountered and the sample size. Where possible, these measurements are drawn from biometrics stored in the BTO ringing archive (Clark et al. 2004), and are for newly-ringed fully grown birds in Britain and Ireland, mostly measured between 1995 and 2005.
Live weights. No account is taken of diurnal or seasonal variation in weight, which may be substantial in some species. For each age and sex class for which sufficient data are available (>20 measurements) we give the mean ± 1 standard deviation, together with an indication of the range encountered and the sample size. Where possible, these measurements are drawn from biometrics stored in the BTO ringing archive (Clark et al. 2004), and are for newly-ringed fully grown birds in Britain and Ireland, mostly weighed between 1995 and 2005.
Clark, J.A., Robinson, R.A., Balmer, D.E., Adams, S.Y., Collier, M.P., Grantham, M.J., Blackburn, J.R. & Griffin, B.M. 2004. Bird ringing in Britain & Ireland 2003. Ringing & Migration 22:85-127.
Svensson, L. 1992. Identification Guide to European Passerines<?i>. Published privately. Stockholm, Sweden.
Migration blog (15th – 21st October)
Changeable winds over the coming week could herald the first big arrival of Dark-bellied Brent Geese.