Great Black-backed Gull (Larus marinus) 2cy, March 05 2007, IJmuiden, The Netherlands.
Dominant bird over food. Last phase of typical sequence:
(1)
wings bend slightly away from body, neck curved and bill almost touching toes,
(2) wings still folded, neck streched and call in 45 degrees angle,
(3) as in 2, now walking towards opponent,
(4) illustrated below, wings raised, ready to start a fight.