DARTERS, HERONS AND HAMERKOP
Darters (Anhinga melanogaster rufa) must surely rank among the most elegant and graceful of birds. They are frequently seen poised silently atop some dead log or rock jutting from a large expanse of water, sitting quietly for hours on end. The long snake-like neck is held close to the body, occasionally craned when the bird is aroused by an unusual sound or spots a fish below. Although not very common, darters occur along all the major rivers and some of the larger dams or pans. They feed on fish and frogs, diving to catch their prey, some times swimming rapidly with only their heads protruding above the water. Also found wading slowly and serenely in the shallower water of all the major rivers is the grey and brown Goliath Heron (Ardea goliath), largest of all the Park's heron species. It stands about 1,4 meters tall on long, spindly legs and has a long, gracefully curved neck. Very shy birds, they fly off when anyone attempts to approach them, so that binoculars are essential to get a close look at these hand some creatures. Their diet consists of fish.
Probably the most common of the herons is the small, but attractive Green-backed Heron (Butorides striatus). It is found along all the rivers and at many of the dams and pans, preferring to stalk the vegetation-covered edges for a wide range of food such as dragonflies, grasshoppers, butterflies, other insects, frogs, tadpoles, small crabs, spiders and fish. These herons walk with their long necks held tight against the body until a likely-looking prey is spotted. Slowly they creep up to the victim, and then swiftly shoot out the long neck to grasp the morsel. Most green-backed herons are seen singly, although pairs are occasionally found hunting together in summer.
Cattle Herons or Cattle Egrets (Bubulcus ibis) are normally seen in groups of up to a dozen, and though not very common, they are found in open bush throughout the area. These dainty white birds with yellow bills often walk among herds of game, feeding on any insects showing themselves when disturbed by the hooves and movements of the animals. The egrets feed on a wide range of prey, which as well as insects may include lizards and young birds - or frogs, tadpoles, fish and crabs when they feed around pools or dams. In the evenings they fly to the top of dead trees or prominent vegetation to roost communally, providing a peacefully pleasing sight for visitors driving back to camp through the gathering dusk.
Of several other species of heron which are found in the area, per haps the Grey Heron (Ardea cinerea) and the Great White Heron (Egretta alba) are most frequently seen. They are not common, but have been recorded at various localities throughout the Park. Both species are found near water, usually quiet pools in large river beds or at the edges of large dams where they stealthily hunt small water animals such as crabs, frogs, insects, fish, lizards and snakes.
One of the most common of the birds associated with rivers and dams in the Park is the Hamerkop (Scopus umbretta). In Afrikaans, the name means 'hammer-head', which, indeed, the head resembles. These fairly large, brown birds are frequently seen at many of the rivers and dams. They stroll through the shallows, sometimes pecking, sometimes tentatively kicking some underwater object, searching for frogs, fish, crabs, snails and insects on which to feed. They build huge nests in suitable trees close to the water, using sticks, reeds, branches and twigs to construct the dome-shaped structures with their entrances underneath. They may take six months to finish the work, but when completed few predators are able to enter or break the nest.
