Shoebill - Behaviour and Ecology

Behaviour and Ecology

The Shoebill is noted for its slow movements and tendency to remain still for long periods, resulting in repeated descriptions of the species as "statue-like". They are quite sensitive to human disturbance and may abandon their nests if flushed by humans. However, while foraging, if dense vegetation stands between it and humans, this wader can be fairly tame. The Shoebill is attracted to poorly oxygenated waters where fish frequently surface to breathe. Exceptionally for a bird this large, the Shoebill often stands and perches on floating vegetation, making them appear something like a giant jacana, although the similarly-sized and occasionally sympatric Goliath heron is also known to stand on aquatic vegetation. Shoebills typically feed in muddy waters and, being solitary birds, forage at a minimum distance of 20 m (66 ft) from one another. This species stalks its prey patiently, in a slow and lurking fashion. While hunting, the Shoebill strides very slowly and is frequently motionless. Unlike some other large waders, this species hunts entirely using vision and is not known to engage in tactile hunting. When prey is spotted, it launches a quick, violent strike. However, depending on the size of the prey, handling time after the strike can exceed 10 minutes. Around 60% of strikes are successful in yielding prey. Frequently water and vegetation is snatched up during the strike and is spilled out from the edges of the mandibles. Occasionally, the activity of hippopotamus may inadvertently benefit the Shoebill, as the huge mammals occasionally force fish to the surface of the water while they are submerged.

Shoebills are largely piscivorous but are assured predators of a considerable range of wetland vertebrates. Preferred prey species have reportedly included Marbled lungfish and Senegal Birch as well as various Tilapia species and catfish, the latter mainly in the genus Clarias. Other prey eaten by this species has included frogs, water snakes, Nile monitors and baby crocodiles. More rarely, turtles, snails, rodents and small waterfowl have been reportedly been predated. There exists a single report of Shoebills feeding on Lechwe calves, although this would need confirmation. Given its sharp-edged beak, huge bill and wide gape, the Shoebill can hunt large prey, often targeting prey bigger than other large wading birds. Fish eaten by this species are commonly in the range of 15 to 50 cm (5.9 to 20 in) long and weigh around 500 g (1.1 lb), though lungfish of as much as 1 m (3.3 ft) have been attacked. Snakes predated are commonly from 50 to 60 cm (20 to 24 in) long. In the Bangweulu Swamps of Zambia, the main prey items fed to young by the parents consisted of Clarias mossambicus (a catfish) and water snakes. In Uganda, lungfish and catfish were mainly fed to the young.