How rare is a mandarin Duck?

The adult male has a red bill, large white crescent above the eye and reddish face and "whiskers". The male's breast is purple with two vertical white bars, and the flanks ruddy, and he has two orange "sails" at the back (large feathers that stick up like boat sails). The female is similar to the female wood duck, with a white eye-ring and stripe running back from the eye, but is paler below, has a small white flank stripe, and a pale tip to its bill. Both the males and females have crests, but the purple crest is more pronounced on the male. Like many other species of ducks, the male undergoes a moult after the mating season into eclipse plumage. When in eclipse plumage, the male looks similar to the female, but can be told apart by its bright yellow-orange or red beak, lack of any crest, and a less-pronounced eye-stripe. Mandarin ducklings are almost identical in appearance to wood ducklings, and very similar to mallard ducklings. The ducklings can be distinguished from mallard ducklings because the eye-stripe of mandarin ducklings (and wood ducklings) stops at the eye, while in mallard ducklings it reaches all the way to the bill.