Although a much smaller bird than the one last considered, the Hammer-head is only about twenty inches in total length, it is in many ways even more peculiar and interesting, since it combines, in quite a remarkable degree, characters that ally it to both Herons and Storks, a Stork-like Heron, as it has been called. It differs from the true Herons in the absence of powder-down patches, the pectination of the middle claw, and in having ten instead of eleven primaries. It differs, on the other hand, from the Storks in having the Heron-like vocal apparatus, while the skull, Mr. Beddard says, “is on the whole more Stork-like than Heron-like, but it does not show any of the extreme modifications of the Stork type.” There are numerous other structural features suggesting one or the other of these types, and it seems safe to assume that it is closely allied to the ancestral form whence the two groups have originated. Its nearest living relative is probably the Shoe-bill.
It is a bird not larger than a Night Heron, with a somewhat cylindrical body, a large head set on a short, thick neck, and a rather large, compressed bill which has a downward curve at the tip. In color the plumage is an almost uniform earthy brown (umber), whence of course the French name Umbrette. There is a slight gloss of bronzy purple above, especially on the wings and tail, while below it is more ashy brown. The head is very strongly crested, the long crest-feathers being usually borne horizontally, thus somewhat resembling a hammer and giving rise to its common name. The toes are rather long and slightly webbed at the base; the tail of twelve feathers is also moderately long.
The Hammer-head (Scopus umbrella), or Hammerkop, as it is called by the Boers, is widely distributed over tropical Africa, Arabia, and Madagascar, though nowhere very abundant. Andersson states that it is pretty generally diffused over Damara Land, where “it is generally observed singly or in pairs, and is of a fearless disposition, allowing a person to approach within range without difficulty.” It is there often met with during the rainy season, but moves to permanent waters as the rain-pools dry up. Reiche now says it “is sociable only in a slight degree. It is usually found single except at the nest, in wooded districts, watching for fishes with its neck drawn in, or walking with measured steps in search of frogs, which, besides worms, snails, and insects, constitute its food. Its flight resembles that of the Ibises, neck and feet being carried straight out. Its voice is a harsh quack, similar to that of the Spoon-bill.”
The nest of the Hammerkop is described as one of the most remarkable structures made by any African bird, being a huge, flattened, dome-shaped affair,often six feet or more in diameter and containing at least a large cart-load of sticks. It is built on a rocky ledge or perhaps more frequently in some large tree, each nest being the work of a single pair, and made use of for many years, being repaired or added to as required. The nest, which is very strongly built, is provided with a single, rather small entrance ingeniously placed on the most inaccessible side, while within it is neatly plastered with mud and more or less divided into compartments. The nest is made use of by the birds the year round, and not infrequently several nests are found within a short distance, Dr. Sharpe mentioning having seen six or eight within fifty yards. The eggs, three to five in number, are pure white, and small for the size of the bird. Both sexes appear to take part in the duties of incubation, and it is recorded that two and perhaps more broods are reared in a year. The Hammerkop has the habit, similar to that of the Australian Bower-bird, of embellishing its dwelling with any glittering or bright-colored object, such as bits of crockery, buttons, bleached bones, etc.
The birds of this group resemble in a general way the Herons and their immediate allies, having relatively long legs and necks, but they are distinguished chiefly by structural characters, and we may only mention the absence of powder-down patches, and the hind toe elevated above the plane of the others, leaving the more complete characterization to be recorded under the description of the various groups. The suborder is divided into two superfamilies, the Ciconiidae, or Storks and Wood Ibises, and the Ibidae, which embraces the families Ibididae, or true Ibises, and the Plataleidae, or Spoon-bills.