Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
querquedŭla, ae, f. [from the Gr. κερκουρίς, Varr. L. L. 5, § 79, acc. to O. Müller’s conjecture], a kind of duck, perh. the teal, Varr. R. R. 3, 3, 3; 3, 11, 4; Col. 8, 15, 1: aquatiles querquedulae, Varr. ap. Non. 91, 4.