Continuity of Behavior in the Nuttall White-Crowned Sparrow

For the past three years I have studied the behavior of the Nuttall White-crowned Sparrow (Zonottickia leucophwys nuttdli) on the University of California campus at Berkeley.In the spring of 1934, when I began intensive study, the population on the campus comprised about sixteen pairs.Since it would have taken too much time to follow up so many birds, I restricted myself to seven pairs on territories in the center of the campus.These I trapped and banded recognizably with colored bands.The springs of 1934 and 193.5 were devoted to the phases of breeding behavior: copulation, nest-building, incubation, hatching and development of the nestlings and fledging of the young.Thereafter I followed the same birds through the interval between breeding seasons, from the post-nuptial molt in autumn to the beginning of nesting the next spring.During the interbreeding periods I was aware of many familiar elements, scattered manifestations of behavior we are too apt to consider as purely a product of the physiology of the breeding time.Consciously or unconsciously, we stress the discontinuity of breeding and winter behavior.We emphasize changes and beginnings and look on song, territorialism and mutual attraction of opposite sexes as exclusive manifestations of the reproductive period-strictly limited phases which begin and end abruptly.Actually, perhaps, effective breeding behavior is less something new than a coordination of many elements already present, some permanently, some, as far as we can perceive, for short preceding periods.Copulation, nest-building and patrol of territory ceased at or before the fledging of my birds' last brood.On the other hand, the special and continuous interest in the mate as opposed to all others, the observance of territorial boundaries, and the occasional use of full song by the male during every month, of the interbreeding period constituted permanent elements of behavior.Each pair remained on its breeding area throughout fall and winter.Mates foraged and perched together and followed each other about.In some cases the pair remained alone, in others, they were joined by a flock of immature or mateless birds which the male tolerated.Unquestionably, even in the latter cases, when the pair seemed for long periods to be undifferentiated parts of the flock, a definite liaison must have persisted, for with the coming of spring,' the male drove out the sojourning strangers, and the pair remated.It is unthinkable that this represented a revived memory of the previous year.