nd cocks his head, the wings and
tail are not flicked or fanned, and no feather tracts are erected. The
bird, nevertheless, flits nervously from perch to perch when uttering
the call.

5. The _zip_. The male has a special "scold" note of his own that is
heard when an intruder first approaches the nest. Phonetically it is
_zip-zip-zip_. It is not so loud as the _chee_, and the delivery is
more deliberate than that note. If the intruder remains near the nest,
the _zip_ is usually replaced by the _chee_.

6. The generalized call note or _chee_. The call notes associated with
several situations are combined under this subheading since all can be
rendered in English by the same phonetic equivalent--_chee_. The
_chee_ associated with nestbuilding is of moderate pitch and delivered
deliberately at a rate of about 40 per minute. The feeding call of the
adults is a soft slurred _chee_, while that of the nestlings has a
mewing quality. In general, the _chee_ utilized in signal situations
consists of a few repetitions of the basic note emitted at a moderate
pitch. The _chee_ associated with hostile and courtship behavior is
higher pitched and the delivery is much more rapid, approximately 200
per minute. Nolan (1960:240) reports a continuous rate of 25 per five
seconds when an adult Bell Vireo is alarmed. The _chee_ of extreme
anxiety is a loud emphatic buzz, phonetically ZZ-ZZ-ZZ-ZZ.

TERRITORIALITY

The Bell Vireo exhibits "classic" passerine territoriality. Within a
specific area, a pair of this species carries out pair-formation,
courtship activities, copulation, nesting, rearing the young, and
foraging. With the cessation of reproductive activities, a pair
continues to restrict its other daily activities to the same general
area.

_Establishment of Territory_

In early May the segment of the total suitable habitat within which a
Bell Vireo restricts its activities is not rigidly defined and the
first male of the season ranges over an area too large to be
maintained permanently--one that seems greatly to exceed the needs of
breeding. Male 1 (1960), for instance, was first seen foraging over an
area of approximately seven acres. With the influx of other males,
portions of this large tract were usurped and the territory of the
original male was gradually reduced to an area of little more than an
acre.

In this initial period, a male becomes identified with a large area
but is restricted to an area of nearly t