Fig. 4
From: Ecological and phylogenetic aspects of the spring diet of three palaearctic species of swans
Boxplots of the four categories of food consumed by swans in 21 March—28 April. Horizontal line denote the median value, the whiskers represent minimum and maximum content of the food category in the sample, and the box is drawn from the first to third quartile. *Roots, rhizomes and tubers of vascular submerged and coastal plants. **Vegetative parts of vascular submerged and coastal plants