Duck is a Great Western engine.
Season 1 - Races, Bulgy the Vegetable Bus, Duck and the Field Trip, Rusty and Victor, Bears (cameo), Oliver and the Snowstorm, Dave the Diesel (cameo), Rex and the Tires (does not speak), Funny Jokes, and Donald, Douglas and the Fallen Tree (does not speak)
Season 2 - Rosie and the Flying Kipper, Trevor and the Mud, The Magic Railroad, Tim and Tom, Sodor Blackout, The Bees' Knees, and Thomas and the Christmas Surprise (cameo)
Season 3 - Duck and the Aligators, Grumpy George, Musical Whistles, Snowmen, and Duke Returns
Season 4 - Hiro's New Snowplough, The Trouble with Trucks, Runaway Coach (cameo), James the Really Splendid Engine (cameo)