3. Distress call. It was heard only once, when a captured bird was being freed from a net. When the bird was almost disentangled it uttered 10 high-pitched, plaintive notes. The quality of the notes suggested a relationship to the song phrase rather than to other types of vocalization. A nesting pair of Bell Vireos, 10 feet away, became extremely excited when they heard the distress notes. They "scolded" vigorously and flew around my head at a distance of six feet. 4. Alarm note. This is a specialized, three-note call of the male and was heard only from the onset of pair-formation through early nestbuilding. This whinnying, flickerlike call, phonetically _eh-eH-EH_, each succeeding note of which is louder than the one before, is given whenever the male is disturbed by an unfamiliar object. This call is generally succeeded by the _chee_, but occasionally blends into an extended "whinny," and is typically given from some perch affording an unobstructed view of the offending object. The male stretches his neck and 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_