May, 1908 A MIGRATlOxN WAVB OF VARIED THRUSHES 119 



tion was attracted by the sight of a few birds, about the size of robins, flying high 

 and scattered over the sky. This was so unusual at this time of day that I re- 

 marked upon the phenomenon to my companions. 



As the sun cleared the horizon and the light increased we realized the fact that 

 the sky was dotted in every direction with birds flying singly, and at quite an ele- 

 vation, mostly toward the south. As the light grew stronger individuals here and 

 there dropped to a lower altitude and allowed us to discern the fact that they were 

 Varied Thrushes {Ixoreus ncevius). For some time their numbers increased until 

 there were hundreds in sight at once in any direction one might look, and as we 

 were by this time pretty well up on the range we had quite an extended view. 

 Soon we noticed single birds dropping out of the flight and settling in the bushes. 

 These must have been our regular winter residents. Apparently not over one in a 

 hundred dropped out in this way. After nine A. m. the numbers decreased and by 

 ten o'clock the flight was over, with no birds in sight except a few flying from one 

 canyon to another and settling down locally, apparently. I have seen many flights 

 of birds, and migratory flights at that, but only on a limited scale, during many 

 years of observation in California, and yet have never witnessed such a genuine 

 wave of migration, on so vast a scale, as occurred between the hours of six and ten 

 A. M. on the above date. Nor have I seen any mention of this wave having been 

 observed by others. We are not supposed to have such things in California, as the 

 birds generally move more leisurely on this coast when migrating. It would be in- 

 teresting to know if any other members of the C. O. C. encountered this wave. 



San Francisco , California. 



NOTES ON THE WAI^TZING INSTINCT IN OSTRICHES 



By F. W. D'EVEEYN 



ONE evening just as the lengthened shadows in the West proclaimed the 

 advent of early darkness, for there is no twilight in Africa, while driving 

 along the high veldt leading to Pretoria, then but a village nestling among 

 beautiful hedges of rose trees, my Kaffir suddenly startled me by exclaiming 

 "Nance Inje": there is an ostrich! The shrill tone of the interesting announce- 

 ment for the moment threw me off my guard; quickly recovering myself I raised 

 my carbine to my shoulder and sent a 45-caliber bullet after the great grey bird 

 which by that time was making rapid strides in a two-step gait several rods away, 

 that baffled accurate shooting. 



The motion of the bird was peculiar but characteristic of-the species in the first 

 stages of its flight, and was one of the gaits in the strange combination of move- 

 ments so well known to those who are familiar with the birds in their wild or do- 

 mestic state. It was suggestive of a form of dance, indeed in many of its parts not 

 at all dissimilar to the steps in some of the native dances in Kaffir-land. The 

 dance is a rapid whirl suggestive of the turn of the dervish priest; the ostrich how- 

 ever turns first in one direction and then while turning, without slackening speed, 

 suddenly reverses and turns the other direction; the wings are held extended and 

 conform with the alternate raising and lowering of the sides; the head is sometimes 

 held extended forward with the neck outstretched and again held backward with 

 the head erect. Even when going at full speed the bird will suddenly pivot and go 

 directly opposite to its former course. 



