RTH 1963 C. melanotos 16. 17 june Barrow, Alaska She gave a redirt pen as I began to leave the net. Wrote - full frame on center of 20' polygon. - cup was lined over but I gave Several instance of ground contact between 20:37. Both would stand in upright alert posture - about 1-1/2 feet apart. One would sidle up to the other - with head kept up left legs turned toward opponent then a sudden dash at the other - both birds begin fluttering, flapping around toward each other - bills pecking - no other confusion, little detail could be seen - Remotely fighting. Sometimes the two would walk side by side for several feet (~6' one twin, 8' the other) before we would dash at the other. The fighting would end by one bird taking flight - the other following in close pursuit giving the jabber note occasionally a short sequence The hovering. Once when both were on the ground, they separated after flying 10' and each performed a aerial display over its own territory. These encounters took place at a new tentative boundary.