FOOD HABITS OF SHOAL-WATER DUCKS. 39 



Duckweeds are especially abundant on the still waters of southern 

 cypress swamps, often covering the entire surface and furnishing 

 an abundant supply of food for the ducks wintering there. - The 

 stomachs of many of the wood ducks taken in such localities in 

 Louisiana and Missouri were filled almost entirely with duckweed 

 plants, and the gullets also of several of them were crammed. A 

 few ducks from other localities, as Arkansas, Illinois, New York, 

 and Ontario, had taken this food in considerable quantities. Alto- 

 gether, 99 of the wood ducks had been feeding upon greater duck- 

 weed (Spirodela polijrliiza) and 187 on other duckweeds (Lemna spp.). 



PINE FAMILY (PINACEAE), 9.25 PER CENT. 



The pine family was represented in the wood duck stomachs 

 entirely by cone scales and galls from the bald cypress (Taxodium 

 distichum), with possibly a few from pond cypress (T. ascendens). 

 This peculiar diet is indulged in by this duck to a much greater 

 extent than by any other, or probably by any other bird. The 

 cones of cypress are about an inch in diameter, compact and nearly 

 spherical, and when fully mature break up into angular woody 

 scales, each containing a seed. It is these scales which the ducks 

 pick up and which when ground by the powerful gizzards yield a 

 starchy food material in the seeds. Several kinds of insect galls 

 found on different parts of cypress trees also were eaten by the 

 ducks. The kind most commonly taken was a hard, spherical gall 

 made in the cone by a species of cecidomyid fly (Betinodiplosis 

 taxodii). Cypress galls of various kinds were found in 35 of the 

 stomachs, while 183 contained cone scales, some to the extent of 

 100 per cent of the contents. 



SEDGES (CYPERACEAE), 9.14 PER CENT. 



Sedge seeds are common articles of food of the wood duck, though 

 not so much so as of most of the ducks which inhabit open marshes. 

 A species of bulrush (Scirpus cuhensis) which grows in swamps in 

 the Gulf States far outweighed in importance any of the other sedges 

 identified in the stomachs examined. The seeds of this plant were 

 found in 47 stomachs, in several instances from 3,000 to more than 

 5,000 being present. Fifteen wood ducks had eaten the large, 

 beaked seeds of pollywog or beaked rush (RJiynchospora corniculata) . 

 In a series of 3 stomachs from Okefenokee Swamp, Georgia, these 

 seeds constituted 10, 17, and 35 per cent, respectively, of the con- 

 tents. The small, hard, spherical seeds of saw grass (Cladium 

 effusum) were present in 15 stomachs, those of nut rush (Selena 

 sp.) in 3. Seeds of chufas (Cyperus spp.) were found in 45 stomachs, 

 usually in small numbers, and in one stomach from Minnesota was 

 one large tuber of chufa (Cyperus esculentus). Seeds of the genus 



