ame tree in Oklahoma by
Bunker (1910:72); the nest of the black-cap was situated centrally and
that of the Bell Vireo peripherally in the tree. Bell Vireos
invariably place their nests in the outer portions of trees and
peripherally in thickets. This placement would further obviate
interspecific conflict with the white-eye since its nests are placed
centrally in the denser portions of a thicket.

A critical feature of the habitat preferred by the Bell Vireo is the
presence of water. In far western Kansas this species is restricted to
riparian growth along the more permanent waterways. This in itself is
not adequate proof of the significance of water supply because thicket
growth in that part of the state is found only along waterways. The 20
areas over the state that I have visited where Bell Vireos were
present were closely associated with at least a semi-permanent source
of water. Fifteen other areas indistinguishable from the 20 just
mentioned, but lacking a permanent supply of water, also lacked Bell
Vireos. Nevertheless areas in which Bell Vireos typically nest are
decidedly less mesic than those frequented by White-eyed Vireos.

Once the Bell Vireo was probably more local in its distribution being
restricted to thickets associated with permanent water. Clearing of
woodland for agricultural and other use, and subsequent encroachment
of second growth concomitant with the creation of man-made lakes and
ponds, has greatly increased the available habitat for this bird. The
preferred species of shrubs for nesting are reported (Bent, 1950:254)
to be various wild plums (_Prunus sp._). The widespread distribution
and abundance of the exotic Osage orange has greatly augmented the
supply of trees suitable for nesting.

SEASONAL MOVEMENT

_Arrival in Spring_

The subspecies of the Bell Vireo breeding in Kansas, _V. b. bellii_,
winters regularly from Guerrero and the Isthmus of Tehuantepec south
to Guatemala, El Salvador, and northern Nicaragua (A. O. U.
Check-list, Fifth Edition, 1957:469-470). In the United States
migrating birds are first recorded in early March (Cooke, 1909:119).
The Bell Vireo is a relatively slow migrator, moving primarily at
night and covering little more than 20 miles at a time (Cooke, _op.
cit._ 119). The average date of arrival, based on 27 records, for
northeastern Kansas is May 8; the earliest record is April 22, 1925,
from Manhattan, Riley County, Kansas (fig. 2-A).

In 1959 the fi