Black mambas often live up off the ground so birds are common prey. They hunt using active stalking and ambush techniques, surreptitiously following their prey, before positioning themselves and waiting for an opportunity to strike. Weaver birds build their nests on the ends of the skinniest branches, often over water and far from reach. Even a mamba finds this a challenge. Nonetheless, the snake's remarkable strength means it can stretch itself out over gaps of more than a metre to reach the nests and move from tree to tree without coming down to ground level. The birds mob the mamba in a combined attempt to drive it off.