PROPAGATION OF WILD-DUCK FOODS. 



37 



Thirty-seven canvas-backs collected at Lake Surprise had eaten 

 various parts of this plant to the extent of 71.6 per cent of their diet. 

 This is a second illustration of the unusual phenomenon of the canvas- 

 back's being attracted to shallow water by a highly prized food. 

 Six ring-neck ducks, or blackjacks, made more than 91 per cent of 

 their food of this plant, and two southern black ducks (Anas ful- 

 vigula) 98 per cent. The following ducks also were feeding on the 

 plant: Mallard, pintail, lesser scaup, redhead, and shoveller. The 

 parts eaten are the rootstocks, stolons, tubers, and seeds. Mr. Charles 

 W. Ward has furnished rootstocks of Castalia mexicana from Avery 



Fig. 32. — Two types of leaves of banana waterlily. (The larger outline half natural 



size. ) 



Island, La., with the information that this plant and wild celery 

 (Vallisneria spiralis) furnish the bulk of the food of canvas-backs 

 in that locality. • 



DESCRIPTION OF PLANT. 



The banana waterlily is the only native species of the group of 

 true waterlilies (as discussed above) that has yellow flowers. But 

 the leaves and flowers of this species may either float on the sur- 

 face of the water or stand a few inches above it. The leaves are 

 green above with brown mottlings and vary from greenish to purplish 

 red below with small black markings. The edges of the cleft of the 

 leaf are either somewhat separated or overlapping (fig. 32). The 



