126 Kennakd, Ferruginous Stains on Waterfowl. [ April 



bird has changed its feeding ground to a locality where there is no 

 ferric oxide present. 



The next question is, — why, when the stain does occur, should 

 it be confined so generally to the heads of the birds under consider- 

 ation. As a matter of fact, it is not so strictly thus confined as 

 many people seem to suppose, but occurs frequently on their bellies 

 and tibiae, and less often on their breasts. 



In the case of the Blue Geese, with whose feeding habits I am 

 familiar, the stains on their heads seem undoubtedly due to their 

 method of feeding about the shallow sloughs among the marshes 

 and flats along the Louisiana coast. The crops of all those birds 

 which I have examined, which contained anything at all, were full 

 of the roots of certain tall, grass-like plants, which grew about the 

 shallow sloughs and wet flats, but which I did not identify. What 

 seems a simple explanation is, that the feeding bird, standing in the 

 shallow water with his belly usually clear of the surface, sticks its 

 head beneath the surface and digs with its bill in the mud among 

 the roots of the grasses and decayed vegetation, riling the muddy 

 water, and gradually by repeated application acquiring a deposit 

 of oxide of iron upon its forehead and cheeks, and perhaps the rest 

 of the head and neck. It is possible that the alternate wetting and 

 drying may aid in the deposit. If the water be deep enough, so 

 that the tibiae, belly and breast become immersed, these parts of 

 the plumage may also become discolored. The deposit seems to be 

 rapidly acquired. 



Mr. W. L. McAtee of the Biological Survey has written very 

 fully of the habits of the Blue Goose in feeding on the roots of certain 

 grasses. 1 



I am not personally familiar with the feeding habits of the other 

 members of the genus Chen, except with those of the few Lesser 

 Snow Geese that consort with the Blue Geese in southern Louisiana. 

 Their feeding habits, so far as I have been able to observe, are 

 exactly like those of the Blue Geese, digging just as they do for 

 their food among the grass roots of the marshes and shallow sloughs. 

 It seems reasonable to infer, however, that the other members of 



1 Notes on Chen caerulescens, Chen rossi, and other Waterfowl in Louisiana. ' The 

 Auk,' July, 1910, pp. 337-339. 



