t 2 feet 3 inches high in
small trees and shrubs averaging 11 feet 2 inches in height.

8. Nestbuilding is intimately associated with courtship and is a
responsibility of both sexes. The male builds the suspension apparatus
and the female constructs and lines the bag. Both sexes participate in
adorning the exterior. Construction lasts from four and one-half to
five days.

9. The nest is compact, pendant, and composed of strips of bark and
strands of grasses that are interwoven and tightly bound with animal
silk. Nests built in May are bulkier than those constructed later in
the season.

10. Egglaying begins on the first or second day after the nest is
completed. The eggs are deposited early in the morning. The average
clutch-size of the Bell Vireo in Kansas is 3.39 eggs.

11. Both sexes sit on the eggs, but only the female truly incubates
because the male lacks a brood patch. Incubation lasts fourteen days.

12. The Bell Vireo is double-brooded in "good" years.

13. Nesting failure resulted from severe weather, predation,
parasitism by cowbirds, and human interference. Behavior that
contributes to nesting failure is selection of an unfavorable
nest-site, singing on and near the nest, and the tendency to flush
from the nest in view of potential enemies.

LITERATURE CITED

AMERICAN ORNITHOLOGISTS' UNION

1957. Check-list of North American birds. Fifth ed. Baltimore,
The Lord Baltimore Press, The American Ornithologists'
Union, iv + 691 pp.

ANDREW, R. J.

1956. Intention movements of flight in certain passerines, and
their use in systematics. Behaviour, 10:79-204.

BAILEY, R. E.

1952. The incubation patch of passerine birds. Condor,
54:121-136.

BENNETT, W. W.

1917. Bell's Vireo studies (Vireo bellii Aud.). Proc. Iowa
Acad. Sci., 24:285-293.

BENT, A. C.

1950. Life histories of North American wagtails, shrikes,
vireos and their allies. Smithsonian Inst., U. S. Nat.
Mus. Bull., 197:vii + 411 pp., 48 pls.

BUNKER, C. D.

1910. Habits of the Black-capt Vireo (Vireo atricapillus).
Condor, 12:70-73.

CHAPIN, E. A.

1925. Food habits of the vireos; a family of insectivorous
birds. U. S. Dept. Agric. Bull., 1355:1-44.

COMMON, M. A.

1934. Notes on a Red-eyed Vireo's nest. Auk, 51:241-242.

COOKE, W. W.

1909. The migration of vireos. Bird Lore, 11:78-82, 11