ansas. The 15 acres adjacent to
this on the southwest is owned by the University of Kansas Endowment
Association, but is used by Mr. E. H. Chamney for the grazing of
cattle. This portion is bounded on the west by a stone fence, beyond
which lies a 14-acre field of natural prairie owned by Dr. C. D. Clark
that is bordered on the extreme west by a narrow thicket of elm
saplings.

The principal topographic feature of the area is an arm of Mount
Oread, that rises some 80 feet above the surrounding countryside.
About 200 feet from the crest of the southwestern slope of the hill a
40-foot-wide diversion terrace directs run-off toward the two-acre
reservoir that is the source of water for eight experimental fish
ponds of the laboratory.

The predominant shrub-vegetation consists of Osage orange (_Maclura
pomifera_), honey locust (_Gleditsia triacanthos_), and American elm
(_Ulmus americana_). These saplings, ranging in height from 3 to 25
feet, grow in dense thickets as well as singly and in clumps of twos
and threes. Larger trees of these same species grow along the crest of
the hill, along the eastern and southeastern boundaries of the area,
and along the stone fence separating University land from that owned
by Dr. Clark. A dense growth of coralberry (_Symphoricarpos
orbiculatus_) forms the understory just below the crest of the hill.
Isolated clumps of dogwood (_Cornus drummondi_) and hawthorn
(_Crataegus mollis_) are scattered throughout the area. These species
of shrubs grow densely along the stone fence. The isolated thicket on
the Clark land is composed primarily of elm and boxelder (_Acer
negundo_), but includes scattered clumps of dogwood, Osage orange, and
honey locust. Poplars (_Populus deltoides_) are the only large trees
in this area.

[Illustration: FIG. 1. Map of the study area near the
University of Kansas Laboratory of Aquatic Biology. The dashed
lines mark the approximate territorial boundaries of the
original nine pairs of Bell Vireos from May 1960 to early June
1960.]

The open areas between the thickets are grown up in red top (_Triodia
flava_), bluestem (_Andropogon scoparius_), Switchgrass (_Panicum
virgatum_), Kentucky bluegrass (_Poa pratensis_), bush clover
(_Lespedeza capitata_) and mullen (_Verbascum thapsus_). Shrubby
vegetation occupies about 65 per cent of the total area, but in the
Clark portion constitutes only about 35 per cent of the ground cover.

_Consideratio