Imperial units commonly used units for length are (li), (tseung/cheung), (tsek/chek), (tsun/chun), (fen/fan) in descending scale order. These units are now rarely used in daily life, the imperial and metric systems being preferred. The imperial equivalents are written with the same basic Chinese characters as the Chinese system. In order to distinguish between the units of the two systems, the units can be prefixed with "Ying" () for the Imperial system and "Wa" () for the Chinese system. In writing, derived characters are often used, with an additional (mouth) radical to the left of the original Chinese character, for writing imperial units.
Imperial pigeon the Australian pied imperial pigeon, the Torres Strait pigeon or the Torresian imperial pigeon. Imperial pigeons are only found in southern Asia, Australia, New Guinea and the Pacific, a distribution from the Himalayas ("D. badia") to Tahiti in the South Pacific ("D. aurorare"). The greatest diversity of birds is in New Guinea. Imperial pigeons are strong fliers, are capable of flight over oceans, and have been successful in colonising islands and archipelagos. Australia has a poor representation of "Ducula" amongst its fauna, with only one species breeding on the mainland ("D. spilorrhoa"). There is no clear explanation why more species