1350 U.S. NATIONAL MUSEUM BULLETIN 237 paet s 



ing 10 had raised one brood and made one or more further unsuc- 

 cessful attempts. 



Fall and Winter. — Most of the Puget Sound sparrow populations 

 leave their nesting grounds in the fall and form large flocks which 

 persist for 6 or 7 months. I have no first hand knowledge of their be- 

 havior in early fall before migration, nor during the flight south. This 

 account begins with the arrival in California of the populations that 

 winter at Berkeley on the same ground with nultalli. The quotations 

 below are from Blanchard (1941). 



In late September and early October flocks of from twenty to fifty birds reach 

 Berkeley, announcing their arrival by a chorus of song which is unmistakably 

 distinct from that of the Berkeley Nuttalls. 



Arrival dates are not identical for successive years, nor do all birds come on the 

 same day in any one year. From 1934 to 1937 I saw the first Puget Sound spar- 

 rows on the campus on September 27, 30, 13, and 23, respectively. In 1935 a few 

 birds came September 30, but it was not until October 5 that the first large flock 

 arrived. In 1936 I heard a Puget Sound sparrow sing on September 13, and 

 another observer heard one on the sixteenth, but I saw no large flocks until the 

 twenty-sixth. In 1937 the period of arrival extended from September 23 to 

 October 5. 



In spite of the fact that one pair, at least, remated for two or more years on the 

 same territory at Friday Harbor, I have detected no tendency to remain paired 

 on the wintering grounds, no hint of such persistent mutual awareness as might 

 reveal, within the winter flock, mates or nest mates of the past season. The flock 

 is a homogeneous assemblage, without visible subdivision. It is more coherent 

 than the smaller groups of immature Nuttalls. The latter are loose aggregates — 

 individuals foraging on commom ground, unified only by fright. The flocks of 

 Puget Sound sparrows show a continuous simultaneity, a commom responsiveness, 

 producing true flock reactions. 



Once on the wintering grounds the migrants show almost as strong a tendency 

 to localization as do the residents. Year after year four flocks of Puget Sound 

 sparrows have settled, each on a different area on the campus, and from the day 

 of their arrival to that of their departure six months later have never left it but 

 have foraged and roosted regularly at the same spots. Restriction to mutually 

 exclusive areas is the rule, as has been proven at Palo Alto by the banding records 

 of Price (1931). In February, 1928, by banding and by painting the tail feathers 

 of Puget Sound sparrows on the Stanford campus, Price worked out the areas of 

 three flocks and found almost complete mutual exclusiveness. 



The adult Nuttalls are perfectly tolerant of the Puget Sound sparrows for the 

 whole winter season. Even in spring, when the resident males are ready to fight 

 and drive out other male Nuttalls, they allow the pugetensis flocks to wander un- 

 molested through their territories and may even forage peacefully in the midst of 

 the flock, set off from the rest by distinctions which can hardly be based on phys- 

 ical appearance. Differences in individual and flock behavior and in degree of 

 aggressiveness undoubtedly account for the perfect cleavage between the groups. 

 The larger flock of silent birds, obviously with no interest in the ground besides 

 the food they are seeking, suggest no threat, rouse no jealousy. When a Nuttall 

 landowner chances to hop or to fly straight at them, the Puget Sound sparrows 

 always give ground, even to the extent of relinquishing a morsel of food too large 

 to carry off. 



