ns of Habitat_

Nolan (1960:226), summarizing the available information on habitat
preferences of the Bell Vireo, indicates that this species tolerates
"a rather wide range of differences in cover." He pointed out that a
significant factor in habitat selection by this species may be
avoidance of the White-eyed Vireo (_V. griseus_) where the two species
are sympatric.

In Douglas County where the Bell Vireo is the common species, the
White-eyed Vireo reaches the western extent of its known breeding
range in Kansas. At the Natural History Reservation of the University
of Kansas, where both species breed, the Bell Vireo occurs in "brush
thickets in open places" (Fitch, 1958:270) and the White-eyed Vireo
occupies "brush thickets, scrubby woodland and woodland edge" (Fitch,
_op. cit._, 268). Along the Missouri River in extreme northeastern
Kansas, Linsdale (1928:588-589) found the White-eyed Vireo "at the
edge of the timber on the bluff, and in small clearings in the
timber," while "the Bell Vireo was characteristic of the growths of
willow thickets on newly formed sand bars." Elsewhere in northeastern
Kansas I have found the Bell Vireo in shrubbery of varying density and
often in habitat indistinguishable from that occupied by White-eyed
Vireos at the Natural History Reservation. In the periphery of the
region of sympatry the rarer species is confronted with a much higher
population density of the common species and consequently might well
be limited primarily to habitat less suitable for the common species.
This would seem to be the case in eastern Kansas, presuming that
interspecific competition exists.

The Bell Vireo has followed the prairie peninsula into Indiana, aided
by the development of land for agriculture. In nearby Kentucky where
thousands of miles of forest edge are found, and where little brushy
habitat of the type preferred by the Bell Vireo occurs, the White-eyed
Vireo is abundant whereas the Bell Vireo is unknown as a breeding bird
(R. M. Mengel, personal communication).

In more central portions of the area of sympatry, nevertheless, the
two species do occur within the same habitat (Ridgway, 1889:191; Bent,
1950:254) and occasionally within the same thicket (Ridgway, in
Pitelka and Koestner, 1942:105); their morphological and behavioral
differences, although slight, probably minimize interspecific
conflict. The Bell Vireo and the Black-capped Vireo (_V.
atricapillus_) have been found nesting in the s