fae vO DW BON BULLETIN 
Published Quarterly by the 
MinaeN Olesir Ay Ui) UB ON S.0.G 1 BT-y: 
2001 NORTH CLARK STREET, CHICAGO, ILLINOIS 
Number 35 September, 1940 
Nesting Habits and Behavior of Bell’s Vireo 
By A. DAWES DUBOIS 
WHILE EXPLORING an old orchard in Logan County, in central Illinois, on 
the 4th of June, 1913, I heard a strange song issuing from an apple tree 
near the edge of a raspberry patch. The small singer was gileaning its 
food from the twigs and leaves. The field glass made manifest an iris so 
dark as to be indistinguishable from the black pupil. In short, my new 
acquaintance turned out to be Vireo belli belli. 
Next morning both the singer and his mate were present, and by 
watching them I found their nest in the raspberries. One twig of the 
supporting fork was broken, so that the nest was hanging by only one 
edge. It still held four eggs, which the vireo was incubating despite their 
perilous situation. On the ground beneath was the empty shell of a cow- 
bird’s egg, about one-third of which had been broken away at the larger 
end. The nest was evidently doomed to failure, so I removed it. 
The birds remained in the vicinity, the male continuing in song, as 
observed on the 11th and 13th of June. By the 21st of July, forty-six 
days after the removal of the first nest, these vireos had a family of well 
grown youngsters on the wing. The young were in the apple trees glean- 
ing most of their own food, but while I was watching, one of them was 
fed by a parent, whereupon it fluttered its wings delightedly. Their father 
was still in song. 
I had no further opportunity to observe this species in Illinois until 
1922. On the 17th of June I came upon a Bell’s vireo talking in his 
intense manner from his station in an oak tree at the side of a road in 
the outskirts of Springfield. The next day I found the nest, apparently 
just completed, in one of the bushes of a thicket beyond the oak, and both 
birds of the pair were then in the vicinity. The male on this occasion 
accompanied his singing with a nervous fluttering of wings and tail. His 
mate remained very quiet and watchful. Ten days later I seated myself 
under a bush thirty feet from the nest. The male sang his customary son? 
from a bush behind me, and also a squeaky gabble I had not previously 
heard. He delivered some interrogative sentences, and, in addition, used 
notes like the scolding notes of a wren. From a twig above he took 
a green larva half an inch long. Subsequent observations showed that the 
nest remained unused; it appeared that this bird had lost his mate. 
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