The form of the current vessel strongly resembles both the ancient bronze bird-form vessels and those works of the 18th century that imitated them. See a bird-form zun excavated from Taiyuan in 1988, dated to the late Spring and Autumn period, illustrated in Selected Cultural Relics from Local Museums in Shanxi, Shanxi, 1995, p. 84, no. 123. As on the present lot, the aperture at the top of the back retains a cover, although on the excavated example, it is attached to the handle by a chain.
By the Qianlong period, the interest in the reproduction of archaic forms had reached its peak. See an archaistic bronze bird-form vase on wheels, illustrated by R. Kerr in Later Chinese Bronzes, Victoria and Albert Museum, 1990, p. 77, where the author also illustrates a page from the 1908 version of the Xiqing Gujian (Catalogue of Xiqing Antiquities), originally compiled in 1749, detailing a bird-form vase on wheels. This popular form was copied by artists of the period who worked in a multitude of media, although jade seems to be amongst the most favored. See a Qianlong period jade fenghuang bearing a large vase on its back, illustrated in Zhongguo Yuqi Quanji - 6 - Qing, Hebei, 1991, p. 151, no. 229. However, this form continued to remain popular well after the Qianlong period, as evidenced by another example of the type in green jade, illustrated ibid., p. 104, no. 156, where it is dated to the late Qing dynasty.