172 NYROCA AMERICANA 



the vegetable food. The seeds are the only parts of sedges that are commonly eaten 

 and the numbers taken from individual stomachs run well over one thousand in 

 several cases. 



Grasses, mostly wild rice, made up only 7.50%. Wild celery was taken from 

 17 stomachs and comprised but 2.36% of all the vegetable food, the winter buds 

 and the tender leaves being the parts which the ducks preferred. Other families of 

 plants went to make up the general diet: water-lily seeds, water milfoils, duck-weeds, 

 coontails, smart-weeds and miscellaneous vegetable matter, none of it of economic 

 importance. 



Red -heads in this series took animal food to the extent of only 9.14% and among 

 this the mollusks were, of course, the most important : at least 2400 shells of a small 

 fresh-water snail were present in one stomach and, in all, 26 different species of shells 

 were identified. Insect food was not important (2.53%) because most of the ducks 

 studied were taken in winter, but the few that were shot in the early autumn con- 

 tained a relatively higher percentage of insects. There were only two stomachs that 

 held any remains of fishes. Four birds had eaten crustaceans. 



It seems that where they are feeding on salt or almost salt water they take some of 

 the finer and shorter Zoster a (eel -grass) which grows on sandy bottom. They cer- 

 tainly do not like the long coarse Zostera which we see commonly on the New England 

 coast. I have noticed that in Pamlico Sound, North Carolina, where these ducks 

 feed over the same bottom as Greater Scaup, the food of the Red-head is almost en- 

 tirely vegetable and their flesh excellent, while the Scaups are packed full of shell-fish 

 and are pretty inferior table birds. 



Audubon, who is apt to lay stress on the more unusual food, mentions having 

 found their stomachs crammed with young tadpoles, and small water "lizards" 

 (newts) as well as blades of such grasses as grow around the banks. On several occa- 

 sions he relates having found "pretty large acorns and beechnuts in their throats, 

 as well as snails, entire or broken, and fragments of the shells of various small unios, 

 together with much gravel." 



Two stomachs taken from birds shot in the Athabasca delta in June contained 

 96% animal matter (U.S. Biological Survey). 



Courtship and Nesting. On their northern migration Red-heads pair later 

 than some of the common surface-feeders, particularly Mallard and Black Duck. 

 Recent investigations in the Mississippi Valley, by the U.S. Biological Survey, seem 

 to show that the diving ducks attain sexual maturity comparatively late. 



The display postures of the Red-head (see Plate 57) are so similar to those of the 

 Pochard that great detail will not be necessary here. The male throws back his head 

 at frequent intervals so that the occiput touches the lower back but he does not use 

 the kicking motion of the Golden-eye. I do not think that the throw-back is performed 



