The gourd is a Daoist symbol of immortality and longevity, a subject particularly popular during the Jiajing period due to the Emperor's devotion to Daoism.
An example of a similarly sized (2.4 in.) miniature double-gourd vase, dated to the Xuande reign, decorated in underglaze blue and white can be found in the Meiyintang Collection, illustrated by R. Krahl, Ceramics from the Meiyintang Collection, vol. 4 , London, 2010, no. 1657. Krahl catalogues this vase as a bird feeder.