Twitched a Ferruginous Duck found by Dave Richardson at Castle Howard this afternoon. A fine drake, with pure white wingbars and undertail coverts, pale eye, nice black bill nail, solid dark upperparts and rich chestnut head and breast, concolorous with flanks. Dark rear border to flanks setting off white undertail nicely. White belly patch noted when the bird roll-preened. A smart bird, though very active which made it tricky to pick up at first. Also noted, Russ Slack and Ollie Metcalfe, plus c30 Tufties, c50 Wigeon and a Chiffchaff. Despite Russ giving me a go with his scope - I'm using an old Kowa at the mo - I failed to get any decent pics, though one does illustrate the wingbars nicely.