24 BULLETIN 672, U. S. DEPARTMENT OF AGRICULTURE. 



and mallards wore not far behind in this respect. Some of the birds 

 treat cm I in this way became tame at once, while others seemed never 

 to lose their sense of fear. 



Birds vary somewhat in the degree to which they are affected and in 

 the manner in which they recover. A few pintails and green-winged 

 teal handled during 1916 seemed to suffer some breakdown of the 

 nervous system as a result of the severe paralysis. As these indi- 

 viduals recovered from their helpless condition they had little or no 

 control over their muscular movements, though the} 7- seemed normal 

 in other ways. There was a constant trembling of the head, and 

 with any attempt at movement head, wings, and feet were thrown 

 about convulsively. As it raised its head in attempting to drink, 

 such a bird might throw itself completely over, or in trying to swim 

 to shore might dash in circles about the pen, turning over and over. 

 Birds affected in this way, however, were comparatively rare. None 

 of those under observation recovered. 



Birds that are seriously sick get very thin as they recover, but 

 soon regain their normal flesh. Sick ducks in captivity should be 

 fed morning and evening. The writer used wheat and barley mixed 

 in equal parts as food for the larger ducks. Teal seldom eat any- 

 thing but wheat. The grain was placed in shallow wooden troughs 

 5 feet long, from 4 to 6 inches wide, and 1£ to 2 inches deep. These 

 troughs were placed across the pen a foot or so from the edge of the 

 water. In this way the grain was brought to the notice of the birds 

 as they went in and out of the water. In addition to grain it is well 

 to have a small pan of grit in each pen. 



During hot weather half of each pen should be covered with rushes 

 in order to protect captive birds from the sun. Though able to 

 endure intense heat when free, birds may succumb when confined in 

 a narrow space unless protected. On Bear River it was necessary 

 to inclose that part of the pens projecting into the water as a pro- 

 tection against the inroads of the numerous carp. Along the river 

 banks in low water during summer a margin of mud is exposed that 

 separates the roots of the riparian vegetation from the w T ater. This 

 deprives the carp of a large part of their natural feeding grounds, so 

 that grain and excrement about the duck pens proved a great attrac- 

 tion to them and they frequently dug out the mud under an entire 

 pen in the course of a night. Racks 6 or 8 feet long were made of 

 lath sharpened at one end and nailed to crosspieces, with half-inch 

 spaces. With these a fence was built in the water 3 feet beyond the 

 pens and the same distance from either end. This permitted free 

 circulation of w T ater and at the same time kept the carp from digging, 

 as the lath were sunk from 6 to 12 inches in the mud. It is neces- 

 sary to fill in the duck pens from time to time, as the more active 

 ducks continually dig away the mud from the shore. 



