44 BULLETIN 862, U. S. DEPARTMENT OF AGRICULTURE. 



MADDER FAMILY (RUBIACEAE), 2.25 PER CENT. 



One of the staple articles of food of the ducks feeding in the southern 

 swamps is the seeds of buttonbush (Cephalanthus occidentalis) . Of 

 the total of 413 stomachs of wood ducks, 192 contained these seeds. 

 They were present in 65 per cent of the stomachs from Louisiana, 

 usually in small numbers. Occasionally, however, several hundred 

 were present in single stomachs, in which they made as much as 75 

 or even 90 per cent of the contents. Remains of the seeds of button- 

 weed (Diodia virginiana) were found in 6 stomachs; those of cleavers 

 (Galium sp.). in one. 



BUR REEDS (SPARGANIACEAE), 1.96 PER CENT. 



The hard, nutlike seeds of bur reeds (Sparganium spp.) were 

 present in 53 of the wood duck stomachs. Bur reeds are aquatic 

 plants with ribbon-shaped leaves and with seeds borne in clusters 

 resembling burs at the ends of the branches. .When these seeds are 

 found in duck gizzards the outer coverings are usually worn off, 

 but the hard kernels persist for some time. In 17 instances the 

 seeds were identified as those of the broad-fruited bur reed (Spar- 

 ganium. eurycarpum) . 



FROGBIT FAMILY (HYDROCHARITACEAE), 1.31 PER CENT. 



Remains of the many-seeded fruits of frogbit were found in 12 

 wood ducks' stomachs. Several full stomachs from Louisiana con- 

 tained this food to the extent of from 65 to 90 per cent of their 

 contents. The plant is aquatic, and its berries are fed upon by 

 many species of ducks. Four wood ducks had been feeding upon 

 wild celery (VaUisneria spiralis). One of these, taken from the 

 shallows at the mouth of the Susquehanna River, in Maryland, had 

 swallowed 30 of the sprouting winter buds of the plant, and another 

 from Delavan, Wis., had filled up on the same food. This plant is 

 a much more important element in the food of some of the deep- 

 water ducks, as the red-head and the canvas-back, which obtain 

 the winter buds and rootstocks by diving. 



WALXVT FAMILY (jUGLANDACEAE), 0.91 PER CENT. 



The powerful crushing and grinding ability of the wood duck's 

 gizzard is shown by the presence in 76 of the stomachs examined of 

 fragments of the nuts of the bitter pecan (Hicoria aquatica). These 

 nuts have as hard a shell as any of the northern hickory nuts, yet 

 they are broken as they enter the gizzard and before they can pos- 

 sibly have been exposed to the full crushing power of that organ. 



All of the bitter pecans identified were from ducks taken in Louisi- 

 ana. The entire food of one bird from Mansura, La., consisted of 

 one whole pecan with fragments of several others. Usually pecans 

 amounted to from 5 to 20 per cent of the stomach contents. 



