110 U. S. NATIONAL MUSEUM BULLETIN 211 



Mortality among the nestlings was very high, due largely to a heavy 

 rainstorm accompanied by high wind which destroyed the nests, 

 eggs, and young. Many eggs and young birds were devoured by 

 predators, largely unknown but probably snakes, small mammals, 

 and perhaps birds of prey or crows. "Out of 314 nestlings, hatched 

 from 443 eggs, 215 were destroyed before they were old enough to 

 leave the nest. This gives a percentage of success (i.e., young fledged 

 from the total number of eggs laid) of 22.4." In the Minnesota colonj^ 

 studied by Roberts (1909), all the young disappeared, 100 percent 

 loss, from some unknown cause. 



Fautin (1941a) says that: "A partial post-juvenal molt occurred 

 about the last of July when the plumage of the fledgling was changed 

 to that typical of the first-year birds. During this time the birds 

 left the nesting areas and remained in seclusion in the dense cattail 

 marshes. After most birds had completed their autumn molt they 

 wandered about the fields in large flocks during the day, and returned 

 to the marshes at night." 



Gabrielson (1914) made two interesting observations: 



The method by which the young left the nest was interesting. At 5:38 a. m. 

 one of the young clambered to the edge of the nest, seized one of the supporting 

 reeds with each foot and climbed up them a short distance above the nest, ad- 

 vancing each foot alternately. After going about eighteen inches, the bending 

 of the stalks under his weight brought them in contact with others onto which 

 he went. After travelling in the tops for a little waj r , he commenced to work 

 toward the water, and reaching a broken reed rested a while. In a few moments 

 he proceeded along this reed to another and was soon out of sight. * * * 



I had one glimpse of some of the dangers to which the young Yellowheads 

 are exposed. One of the young from a neighboring nest was sitting on a reed 

 about two inches above the water when the jaws of a hungry pickerel rose from 

 the water and the nestling disappeared. It was done so quickly that if I had not 

 been looking directly at the bird it would never have attracted my attention. 



Roberts (1909) says of the food of the nestlings: "Grasshoppers, 

 various insects and a large black larva of some sort which the birds 

 obtained from among the decayed vegetation in the shallow water 

 along the edges of the slough formed the chief food supply. These 

 larvae were ugly and formidable objects and were thrust down the 

 throats of the young buds with considerable difficulty. On one 

 occasion a female was seen carrying a large flat object, squirming and 

 curling about her bill, which was evidently a leech." 



Mrs. Wheelock (1905) writes: "The young are fed by regurgitation 

 for two days, afterwards by both methods for two days, then entirely 

 by fresh food. Examination of the crops of the broods reared in late 

 June showed, on the first day, snails, waterslugs and larvae all par- 

 tially digested. On the second day, insects denuded of wings, legs, 

 and all hard parts, and thoroughly crushed as well as predigested, 



