Holmes, R. 1959 Calcaris lapponicus 3 9 June Barrow Alaska and land. When this happened, the defenders took flight and chased the other bird over the tundra for about 2 min. This flight-chase was noted in several areas. It consisted of the 2 birds often flying straight up in the air for ~15 feet while "belly to belly" and then tumbling together back to within a foot or 2 of the ground. It appeared that actual contact was made between the two by both the bill + feet. The whole array of events was accompanied by a chatter from both birds. 1400-1630. -15-30 seen in the North Area. Two birds, 18?, 19?. Were seen in an aggressive attack as they raced back and forth over the tundra, then several feet into the air, tumbled to the ground and then the 8 performed the mating display accompanied by a high shrill whistle (F.A.P.). Copulation then took place. Some of the birds appeared to be paired.