SPUBRED TOWHEES 479 



content to remain within the shelter of the brush. In the breeding season 

 the birds are very excitable and readily respond to squeaking noises. This 

 trait is undoubtedly correlated with a feeling of concern for mates or 

 young ; for in midwinter when the reproductive instincts are at a low ebb 

 the Spurred Towhees are not easily to be 'squeaked' out into full vie^v. 



The nest of the Spurred Towhee is a deep cup-shaped affair placed on 

 or sunk in the surface of the ground. One found by Mrs. Joseph Grinnell 

 in Yosemite Valley was a deep cup of pine needles, bark, and grass stems, 

 lined with fine round grass stems and a little black horsehair. It was 

 situated among strawberry plants and under a small chokecherry bush. 

 The four eggs were finely marked with reddish brown on a creamy ground 

 color. Two days after discovery this nest was raided, seemingly by some 

 animal which had burrowed up into it from the ground beneath. When- 

 ever the nest was visited, even after the contents had disappeared, the 

 parents were always in attendance and scolded violently. A second nest, 

 of similar construction, was located under a canopy of dried ferns at the 

 base of a small stump. When first found, on June 12, 1915, it contained 

 4 eggs. On the morning of June 24 it held one young bird, and two more 

 hatched out that same afternoon. The fourth chick died while attempting 

 to crack open its shell. Up to the time the eggs were hatched the owners 

 of this second nest, upon being disturbed, slipped away quietly, but after 

 their brood had emerged they changed their behavior, and were then 

 accustomed to stay about and insistently voice their solicitude. The young 

 in juvenile plumage have streaked breasts, but by fall they have assumed 

 the plumage of their parents. 



In the fall after the breeding season and before the arrival of winter 

 snows, the Spurred Towhees wander higher in the mountains, ranging 

 throughout the greater portion of the Canadian Zone. In late September 

 and in October they have been seen on Ulilouette Creek above the falls, 

 on the Snow Creek trail at 6000 feet, and at 7000 feet, near Aspen Valley. 

 This spilling upward is thought to be due to overpopulation of the lower 

 zones as a consequence of the appearance of the fully grown young of 

 the year. It has been further suggested that the young of the year, among 

 animals generally, exhibit instinctively a sort of wanderlust, of benefit 

 to the species in that new territory is thereby sought out and sustenance 

 made available for an increased number of individuals. Of course, when 

 winter comes on, burying the food at the higher levels, this wave of vagrant 

 individuals is pressed back again; but beneficial readjustments doubtless 

 occur in the population even within the regularly occupied area. 



