Small or large flocks of Grey-headed Gull occur at large inland waters (where they breed) and at the coasts.
Grey-headed Gull can be linked to a hysterical cackling.
Grey-headed Gull species breeds with Hartlaub's Gull. Breeding takes place from July to November. Eggs 2 - 3, ground colour blue-green to rich brown with variable dark brown blotches.
Immatures have white heads with dark smudges behind eyes on nape, differing from Hartlaub's Gull in having fleshy-brown legs, a longer flesh-coloured bill with a dark tip and black tail-tip.
Adult Grey-headed Gulls have all-grey hood, pale yellow eyes and bright red bills and legs. When non-breeding, the head is white.
Common to abundant resident.
Grey-headed Gull is a fresh water Gull found on large lakes and dams. Seen fairly regularly but nevertheless still considered an uncommon visitor to the south-western Cape from further north.