ed | Dimensions
-------------+--------------+-------------
1. | May 3, 1960 | 1.6 acres
2. | May 5, 1960 | 0.6 acre
3. | May 7, 1960 | 0.26 acre
4. | May 11, 1960 | 1.03 acres
5. | May 12, 1960 | 2.07 acres
6. | May 14, 1960 | 3.1 acres
7. | May 13, 1960 | 1.7 acres
8. | May 14, 1960 | 0.46 acre
9. | May 14, 1960 | 0.4 acre
-------------+--------------+-------------
Average 1.25 acres

_Maintenance of Territory_

Except in the early stages of nesting, territory is maintained
primarily by song. In the period of incubation a male regularly
patrols his territory between sessions of sitting on the eggs. He
sings several songs from each of several perches. A male follows a
predictable path, rarely traveling more than 150 feet from the nest.
Incipient patrolling is seen early in the breeding season when
territorial boundaries are in a state of flux.

The male White-eyed Vireo travels a semi-predictable route, as does
the Solitary Vireo (R. F. Johnston, MS). According to Lawrence
(1953:50), the male Red-eyed Vireo has a distinct singing area
completely divorced from the nest area dominated by the female.
Southern (1958:109), working with this same species in Michigan, did
not recognize separate areas, but found that the male wandered
randomly over the territory.

In a species so highly active as the Bell Vireo, the degrees of
hostile action associated with an encounter overlap in such a fashion
that no clearcut distinction can be drawn among the various displays.
Nevertheless, certain generalized patterns are characteristic of all
situations in which members of this species are in a state of anxiety.
The threat displays described in the succeeding paragraphs may all be
utilized within as little as two minutes; mutual agonism may be
terminated at any stage by concerted attack of the dominant bird.

1. Vocal threat. When an intruder is discovered the resident male
markedly increases his rate of singing. The alarm note, _eh-eH-EH_, is
the first call uttered during the nestbuilding and egglaying periods.

2. Head-forward threat. If the intruder does not flee, the resident
male adopts a specific threat posture. The head and neck are extended.
The feathers of the crown are erected, but those of the body are
sleeked. The bird crouches slightly