The four areas are as fellows: 



1. Cuba Islan d , near the mouth of the Sangamon hiver. 

 This area had senistabilized water levels; rice cut-^rass and marsh 

 smartvifced formed the two raajor food plants. Duck gls-zards exajnined 

 from this area totaled 289. 



2. Crane Lake and a marsh adjacent to it, in the vicinity 

 of Snicarte. The lake had fluctuating water levels in 1938; tlie 

 marsh semistable v.ater levels. Duck gizzards examined from this 

 area totaled 293. 



3. Lake Chautauqua and Clear Lake , which lie adjacent to 

 each other, north of havana. The former had a stable v»-ater level, 

 with an abiondance of coontail, longleaf and sago pondweeds and marsh 

 smartweed. The latter had fluctuating water levels and a paucity of 

 duck food plants. While all the duck gizzards were collected at 

 Clear Lake, field observations indicated tr.at the ducks obtained 

 most of the natural food from Lake Chautauqua. Gizzards exam.ined 

 from this area totaled 358. 



4. Duck Island , a s"..ort distance fron Lake Chautauqua and 

 CJ-ear Lake, had semistabilized water levels. Coontail, marsh sm.art- 

 weed and duck potato v;ere the nost important native duck food plants.. 

 .Duck.- gizzards examined from tx.is area totaled 207. 



V.ATERFOV.L FOODS ON FOUR AREAS 



In table 1 are listed the 20 aquatic plants that occurred 

 in greatest abundance in the four areas considered as a whole. Of 

 these, onlj^ eight were used extensivel;r for food by waterfowl. This 

 table presents -a^comparison between ..abundance and use of waterfowl 

 food plants, virit} an index rating of their value for the study areas 

 considered as a vvhole. 



In order to illustrate the effect of environmental condi- 

 tions, v;hicli alter the value of duck food plants in different types 

 of habitat, the abundance, use and index ratings of duck food plants 

 sumirarized in table 1 are presented for each of the four sample areas 

 in tables 2, 3, 4 and 5. 



