The Relation Between Organization and Function of Song in Cardinals

Abstract1. This paper represents an attempt to relate the organization of song in North American cardinals to the manner in which song is used. 2. Each cardinal has several distinctive song types in common with his neighbours. When singing each male sings a series or bout of one song type, followed by a series of another song type. 3. Often when two or more cardinals are singing simultaneously, the song types of the singers are the same. 4. Matching was recorded from males singing under natural conditions. It usually ranged from between 25 and 50% of the time the birds were singing together, although the differences in the amounts of matching by the different pairs of males were not significant. Two males did match significantly more when closer together than when further apart. 5. The relative amount of matching by two males was noted when brought together at the common boundary of their territories. One of these males was also provoked into considerable singing and matching by a tape recorder and decoy placed inside his territory. In both cases the amount of singing and matching was higher than in the normal situation. Also, the latencies of matching were much shorter, as were the bouts. 6. A male exposed to repeated recordings on five successive occasions showed almost perfect matching on the first occasion, but decreased the amount of matching regularly thereafter. The amount of matching was found to be consistent with other variables of song. 7. Matching of song types occurred to a high degree between mated males and females, in fact, to a higher extent than between males. Females do not sing very often so the total amount of this matching with the males is probably no higher than between males. 8. The peculiarities of the organization of song in cardinals are interpreted as reflecting a feed-back system by which homoeostasis of the territorial system is maintained, and as such it permits the co-ordination of the singing of two individuals. Under high stimulation the co-ordination becomes more precise with higher amounts of matching, shorter latencies of matching, and more changes of song type per unit of time. 9. In addition to being used by cardinals, this kind of communication occurs among other members of the Fringillidac and Paridae. All of these species exhibit long tenure of territory throughout the year and some, at least, over several years.