BIRDS IK RELATION TO THE ALFALFA WEEVIL. 17 
YELLOW-HEADED BLACKBIRD. 
( Xanthocephalus xanthocephalus. ) 
The yellow-headed blackbird, or soldier bird, as he is more fre- 
quently called in the West, is the last of the three blackbirds to arrive 
in large numbers, although a few individuals are said to remain 
throughout the winter in favorable localities. 
Nestling and juvenile birds. — As weevil enemies young yellow- 
heads do not rank as high as the nestlings of the other blackbirds. 
The insect amounted to 4.27 per cent of the stomach contents and 
occurred in 40 of 68 birds collected in June. Larvse were preferred 
to adults, being taken on an average of 4.13 per bird, as compared 
with 0.74 for the latter. One nestling 4 or 5 days old had destroyed 
48 larvae, and a brood of three had eaten, respectively, 42, 25, and 40. 
The work of a colony of about 15 or 20 yellow-heads upon an 
alfalfa field of three or four acres came under the writer's observa- 
tion. The breeding marsh was fully half a mile from the source of 
food supply, and the flight of the parent birds to and from their 
nests was observed for about a half hour, during which the adults 
made visits to the fields at the rate of about one every minute. 
Other animal food of the young, strongly indicative of the aquatic 
environment in which the bird lives, was dragonflies and their 
nymphs, which formed 43.86 per cent of the stomach contents, and 
occurred in all but 10 of the 68 stomachs. Some stomachs contained 
fragments of adult Odonata, which testifies to the ability of these 
birds to capture insects generally supposed to be effectively protected 
by their powers of flight. Caterpillars formed about a fourth 
(24.08 per cent) of the food. Ground beetles (5.7 per cent) , spiders 
(5.54), grasshoppers (4.09), snails (3.76), and Hymenoptera (2.1) 
were the principal other ingredients of the animal food. The vege- 
table portion (2.13) was mainly rubbish. 
Two juvenile birds collected in July had eaten the weevil, one of 
which had taken 2 adults and 30 larvse. 
Adults. — During April and May only two adult yellow-heads were 
collected each month, a too limited number to allow definite conclu- 
sions, but it shows that the birds were already preying upon the 
insect. One collected on the 23d of April had eaten a single adult, 
while the bulk of the stomach contents consisted of caterpillars. This 
latter element also composed 97 per cent of the food of the other 
April bird. The two birds taken in May had fed upon the insect, 
having eaten three and seven adults, respectively, which averaged 
10 1 per cent of their food. 
Of 21 stomachs collected in June only 4 failed to contain the 
weevil. The insect formed 43.48 per cent of the yellow-head's food 
and was taken at an average of more than 6 adults and 47 larvae per 
43778°— Bull. 107—14 3 
