Colour-marked birds: a reminder In general, we do not publish separate requests on this subject (there are too many local studies to include them all). If you see a bird marked in some way (other than with ordinary BTO rings), please report it as follows: WADERS: Wader Study Group, C. J. Thomas, Zoology Department, The University, Glasgow G12 8QQ. GULLS: Jeff & Alison Kew, 38 The Spinney, Bar Hill, Cambridge CB3 ssu. WILDFOWL: Carl Mitchell, Wildfowl Trust, Slimbridge, Gloucester Gi.2 7BT. CORMORANTS AND SHAGS: Dr Robin Sellers, Rose Cottage, Ragnall Lane, Walkley Wood, Nailsworth, Gloucestershire GI.6 ORU. ALL OTHER SPECIES: Kevin Baker, BTO, Beech Grove, Station Road, Tring, Hertfordshire HP23 5NR. Although colour marking may be used in purely local studies (e.g. of behaviour), in the majority of cases, studies of marked populations depend upon co-operation from all observers who sight the marked individuals.