Thomas L. Patterson

Field studies of habituation: III. Playback contingent on the response of the white-crowned sparrow

Abstract Territorial song was played to pairs of breeding white-crowned sparrows. Presentation of the song was contingent on the song of the resident male. Continuous recordings of an extensive sample of the behaviour of the male and female were made. A predicted increase in behaviour elicited by this playback regime, as compared to an invariant presentation of song every 11 s, did not occur. A large amount of variance was accounted for when the subjects were split into two groups on the basis of the number of songs emitted by the male. This latter result was cross-validated with data from two other studies. These results suggest that there is a male state variable that exerts a strong influence on the behaviour of both the male and female member of the pair.

Polygyny in the White-Crowned Sparrow (Zonotrichia leucophrys)

Blanchard ( 1941), in her classic monograph on the White-crowned Sparrow (Zonotrichia leucophrys), referred to one instance of polygyny. Earlier she described this case in more detail (Blanchard 1936: 149): “In winter both females made free of their common mate’ s territory, though with some tendency to localization . . . with the approach of reproduction, however, each female created for herself a subdivision of the main territory which she defended against the other female by loud singing and fighting, and in which she finally chose her nest site.” She reported that these two females were completely intolerant of one another. In five years of observation she found only three cases of polygyny (DeWolfe 1968). During a long-term study of reproductive success, territoriality, and song of the White-crowned Sparrow, we observed several cases of polygyny.

Territory Size in the White-Crowned Sparrow (Zonotrichia leucophrys): Measurement and Stability

The problems involved in reliably measuring bird territories and estimating their stability have often been ignored by ornithologists. Observers frequently use the same technique to measure territories as that used by Noble (1939) and other pioneers. Typically, the observer carries a map into the field and notes where a subject bird flies, sings, or has aggressive encounters during a given period of time (e.g., Ralph and Pearson 1971). This method provides intuitively satisfying results because the birds are interacting without human interference. However, it is often time-consuming, and owing to the rarity of interactions on some territorial boundaries it may not be feasible to wait for these interactions to occur. To avoid some of these problems, Wiens (1969, 1974) proposed a method of mapping territories that he termed the “territory flush” procedure. With this method, an observer approaches a singing male until it flushes from its initial position, and then maps both the flight path and the landing location. In another method, Dhondt (1966) presented Great Tits (Parus major) with a stuffed conspecific model and a recording of their territorial song at different locations in the territory. By noting where the subject responded to the stimulus, he soon defined all of the territorial boundaries in a given area. Some investigators (e.g. Krebs 1971, Howard 1974) have used both approaches interchangeably and have combined the data from them. The methods should be evaluated by using both the standard mapping procedure and the stimulus procedure, and comparing the results as to territorial boundaries. In this study, we used both methods to delimit territories and to estimate their stability throughout a breeding season.