Ciconiiformes

Ciconiiformes include the storks, herons, egrets, ibis, etc. Ciconiiforms are known from the Late Eocene. They are stork-like forms, mostly large wading birds with large bills.

Physical characters: only a single pair of sternotracheal muscles in the syrinx; 16-20 cervical vertebrae; diastataxic (fifth secondary feather absent, but 5th secondary covert is present); feet not webbed; middle claw laterally expanded, (pectinate in some families); intestinal ceca present, nearly always very small; largely fresh water or terrestrial habitat; not filter feeders, mostly feed on fish, crustacea, insects, carrion; do not swim for food; northerly species migrate; most nest in trees; strong flyers with broad wings; altricial young; generally colonial but use of sound uncommon; social communication by displays and "rituals."

In most cultures, at least some members of the Ciconiiformes -- herons, storks, ibis, egrets and so on -- have always had an unusual status as objects of religious or artistic veneration. The attraction is certainly not phylogenetic. The morphologically similar, but unrelated, cranes are treated in the same way. Sometimes hauntingly beautiful evocations of these birds are known from antiquity in, for example, Greece, Africa, Egypt, China and Japan. Certainly the vulturid condors have influenced the art and religion of the American Pacific coast from Alaska to Chile. In Indo-European cultures, by contrast, the long-legged water bird tends to be a comical or even evil figure. The cultural phylogeny of these symbols would be an interesting study in itself, and their relative stability over millennia is surprising. Certainly one of the reasons for the attention given the ciconiiforms is their strange and alien way of moving. That special style of movement, whether perceived as graceful or comically awkward, is emphasized in the behavioral rituals common in the group. Some ciconiiforms are completely silent, and vocalization in most species is fairly limited. Thus, rituals and displays are the primary means of communication.

These behaviors seem to be genetically determined almost completely. In fact, one study analyzed the ritual behaviors of storks as if they were anatomical characters and reconstructed a taxonomic tree almost identical to the trees arrived at by anatomical or biochemical characteristics. The rituals associated with initial mate selection, such as the male's "advertising" of his nest site and the female's expression of interest in the male's real estate, were quite extraordinarilly stable. Behaviors related to later events, such as copulation and pair-bond affirmation seem to be more phylogenetically plastic. Finally, behaviors not related to mating, such as the "anxiety stretch" or aggression displays, were quite variable, but still clearly inherited. This contrasts strongly with the song behaviors of passerine birds, which are strongly influenced by learning and individual experience.

Reference: Slikas, B (1998), Recognizing and testing homology of courtship displays in storks (Aves: Ciconiiformes: Ciconiidae). Evolution 52: 884-893.