Robert W. Ficken

VOCAL REPERTOIRE OF THE BLACK-CAPPED CHICKADEE

Describes the physical characteristics, usages, and probable functions of 11 vocali- zations of adult Black-capped Chickadees and 2 of the young. Some modifications of the vocal repertoire as compared with other passefines are associated with sociality and hole-nesting. The Fee-bee, usually considered the song of this chickadee, is less complex than some call notes and also has some differences in function compared to the songs of other passefines. The two most complex calls (Chick-a-dee and Gargle) are associated with social activities. Vocal signals tend toward sexual segregation, which may be important in a monomorphic species. The vocalizations of this species are compared with those of other parids, and selection pressures acting on the structure of vocalizations are discussed. The more complex vocalizations of this species are being

Responses of Four Warbler Species to Playback of Their Two Song Types

RECENTLY renewed attention has been focused on the communicatory function of avian vocalizations (e.g. Marler, 1967; Smith, 1966). One problem in avian communication studies is determining what the message of a vocalization is for the recipient. The purpose of this study was to use song playback experiments to determine if intraspecific song variants have different messages. Few studies of the role of song have been made in species where each individual has more than one song type, although Hinde (1958) studied vocal responses of Chaffinches (Fringilla coelebs) to their two song types in captivity. Many species of warblers have two song types that apparently differ in motivation and function (Ficken and Ficken, 1962, 1965; Morse, 1966, 1967). The American Redstart (Setophaga ruticilla), Chestnutsided Warbler (Dendroica pensylvanica), and Yellow Warbler (D. petechia) possess an accented ending song (AE) and an unaccented ending song (UE). The Yellow Warbler also sings intermediate songs (IE) (Morse, 1966). In all three species song type AE is given more commonly by undisturbed, unmated males, while type UE songs are more common after pairing and during territorial encounters (Ficken and Ficken, 1965). The Black-throated Green Warbler (D. virens) has two song types, referred to as A and B by Morse (1967).

Courtship and Agonistic Behavior of the Common Grackle, Quiscalus quiscula

THIS paper describes the courtship and agonistic behavior of the Common Grackle. The probable derivation, biological significance, and, in some cases, motivation and function of displays are discussed. Basic information on life history is available in Petersen and Young (1950) and Bent (1958). The Common Grackle has a complex display repertory. This, when fully understood, will greatly contribute to our knowledge of social behavior in general. These observations can also be compared with similar studies of other icterids, thus furthering our understanding of evolution in this group. This study was conducted from August 1957 to May 1960. Most observations were made at two colonies of about 15 and 20 pairs, at Ithaca, New York. In addition, birds were observed in captivity. The Common Grackles of the Ithaca area are intergrades between Quiscalus quiscula versicolor and Q. q. quiscula (see Huntington, 1957).

COMPETITION AND CHARACTER DISPLACEMENT IN TWO SYMPATRIC PINE-DWELLING WARBLERS (DENDROICA , PARULIDAE)

Studies of the interactions of an invading species with an already established close relative provide considerable insight into the question of how partitioning of habitats initially occurs (e.g., Mayr, 1963). Such a situation exists where Yellowthroated Warblers (Dendroica dominica) have invaded the habitat of the Pine Warbler (D. pinus) in the loblolly pine (Pinus taeda) forests of the DelawareMaryland-Virginia Peninsula (Delmarva). The purpose of this study was to determine the morphological, behavioral, and feeding adaptations that permit the coexistence of these two species in a relatively homogeneous environment.