qú is a bound form. It appears almost exclusively in
鼩鼱 (shrew, family Soricidae) - small insectivorous mammals that look mouse-like but are not rodents. Despite the rat radical, shrews are evolutionarily distant from rats. The compound is technical zoological vocabulary; everyday Chinese also uses descriptive names like
尖嘴鼠 (pointed-snout mouse). The character itself is rare outside zoology writing.
