As already noticed by M. di Giampaolo (op. cit.) the recto of the sheet is comparable to other drawings of birds such as one of a dove sold at Christie's, London, 8 July 1975, lot 11, which is connected to the frescoes in Santa Maria della Steccata (1530-9). The dove in the present sheet is also similar to one at Goethehaus, Weimar (Inv. 108; A. Gnann, Parmigianino die Zeichnungen, Petersberg, 2007, no. 808). It could also be related to Parmigianino's etching, The Annunciation (Bartsch XVI.6.2) in which the bird appears in the upper right corner.
The bird on the present sheet, like that at Weimar, was probably a dead one, seen from different angles, rather than studied from life. The same can be said for the study of a frog on the verso, which the artist would hardly have been able to study so carefully and in such detail, if it was alive. The volume and contours of the frog, especially for the study on the left, are beautifully rendered through subtle variations of the tonality and the incised outlines, and through neat, dense hatching that conveys the fullness of its body.
Especially when working at the Steccata, Parmigianino produced a number of drawings of animals that seem to have been incised, pricked or squared, though none of the cartoons for the frescoes have survived (Di Giampaolo, op. cit., nos. 24, 54, 82, 101; and Gnann, op. cit., nos. 802, 805, 806).