Orange neckband with a black two alpha-numeric code.
note 1 : used letters are : A, B, C, D, F, H, I, J, L, N, P, R, S, T, U, X, Y, Z.
note 2 : used numbers are : 2, 3, 4, 5, 6, 7, 9.
note 3 : birds are at the Cotswolds Water Park, Gloucestershire, UK.