Unpacking the rings

These are 10-13 mm high rings from Interrex, with an internal diameter of 9-10 mm. Big, but the right size for ringing Torrent Duck, a project my friend Gerardo is heading up here in Patagonia. I hope to be involved in the survey, which will mean some pretty heavy clambering up frozen water streams in an attempt to locate this declining species in southern Argentina.