Sandhill Crane Mayhew 1952 Feb. 15 4mi. S.E. of Thornton, San Joaquin Co., Calif. at 10 A.M. 6 birds were seen in the air flying west, followed by 4 more. Another 10 were seen shortly behind them. On the ground about 1/2 mile east of the road were seen 4 groups totaling 47 birds. Another 13 were seen flying in behind a row of trees or dropping to the ground about a mile from the road. The birds on the ground are standing still or feeding - very little activity on their part. Approximately 2 miles to the south-east of this group was found a group that numbered over 400 birds. When we arrived, some of them were performing their courtship dance. The birds would jump into the air about 4 feet with wings spread wide, others would have their heads down so that the bill nearly touched the ground, at the same time spreading the wings. The birds didn't seem to be performing for any particular bird, but rather it appeared more as a group dance. Only a few birds of the flock were performing. The remainder were standing quietly by or feeding. In a few moments all the birds were quiet. About 15 minutes later a few birds would dance for perhaps a minute, then stop. Somewhere else in the flock another group of 60 or so would begin to dance for about the same length of time. At times there would be an interval of 4 or 5 minutes when no birds would be dancing. Another flock arrived on the scene from the