|Family||Common Names||No. Species|
|Ardeidae||Herons and Bitterns||59|
|Threskiornithidae||Ibises and Spoonbills||29|
|Introduction||Ibises and Spoonbills||Storks||Herons and Egrets|
The Ciconiiformes are typical 'wading birds', mostly associated with shallow water, they have long legs and long bills which allow them to forage in this habitat. Within this framework they show a considerable range of diversity and the feeding habits of Flamingos are considerable different from those of Adjutant Storks. Some species are still totally dependant on water, spoonbills, wood storks, openbill storks and the larger bitterns are good examples of this. Many however have shown the adaptive efficiency of their basic design and have moved partially away from the water. The extreme examples of this are Abdim's Stork and Bald and Hadada Ibises all of which are more terrestrial than aquatic.
Most of the species in the Ciconiiformes are communal breeders, the notable exceptions being the Bitterns, the Black Stork, Hadada Ibis and Spotbreasted Ibis. Nests are usually built in trees (flamingos, and again the bitterns are the exceptions here)and most colonially nesting species often nest in mixed colonies such that you may find Storks, Ibises and Spoonbills as well as species of Herons and Egrets all nesting together. Many species have seasonal changes in the colour of their legs and bill during the mating season. The pair bond is important in most species and regularly repeated, ritualised, behavioural activities during courtship are common. All the actions displayed are adapted behaviours, adapted from non-reproductive interpersonal displays, which have become ritualised for the courtship display. Some examples are:
|Forward Display||derived from||Forward Threat Posture|
|Aerial Clattering||derived form||Aerial Clattering Threat|
|Arching Display||derived from||Anxiety Stretch|
The Ciconiiformes contains a large number of very attractive, relatively large birds. They are important not only ecologically but as symbols of a healthy planet. It is a crying shame then to learn that over 20 percent of the Ciconiiformes are in danger and nearly all have suffered great reductions in numbers over the last century, some species have wild populations of less than 100 and several have not been seen for a number of years. The main cause for concern is habitat destruction as wetland habitats are among the often drained, either intentionally in order to gain access to the soil for human use or accidentally as a result of poor management of the area as a water resource for an ever growing human population.
Unfortunately, because of their size, they are often the target of hunters, who ,now that they are equipped with modern weapons, are horrendously more efficient than they were for most of the past, this scenario has resulted in the people of Pakistan practically exterminating all the large wading birds that lived there. Other causes for concern are the inevitable attrition that human warfare takes, not only on the environment, but also on the spirit of the peoples living in strife riven lands. This often results in them losing their innate respect for the natural world. This is apparent in much of Asia, which when combined with the greed generated by western entrepreneurs, and the destructive influence of the worst of western culture has a disastrous effect on wildlife in general, but particularly on the larger birds.
Ibises and Spoonbills are two easily recognised groups of birds, both being relatively large in size (range = 19 to 42 inches, 48 to 107 cm)with a distinctive general shape. In flight their necks are held straight out, not curved back in a lying down 'S' as in Herons and Storks. Their long legs and necks are combined with long beak or bill to make them adapt at hunting small prey in wetland habitats. Their bills are downward curving in the Ibises and flattened at the tips into a spoonlike shape in the aptly named Spoonbills. Taxonomically they are listed in two different subfamilies, the 23 Ibises in 14 genera in the Threskiornithinae and the 6 Spoonbills in one genera in the Plataleinae. They both have 11 primaries, though the 11th may be greatly reduced, and 12 retrices (tail feathers).
Ibises and Spoonbills have a patchy but world-wide distribution in temperate and tropical climes, with species occurring where ever suitable habitat is available. They are believed to have evolved more than 25 million years ago in S. America. Fossils of species relating to the Glossy, Puna and White-faced Ibises have been found dating from the Miocene (Plegadis peganus and Plegadis pharangitis). Also among the fossil record are two flightless species, Apteribis glenoo from Hawaii and Xenicibis xympithecus from Jamaica.
Like their relatives the Storks they are primarily wetland birds, and like so many wetland species a number of them are in danger of extinction because so much wetland habitat has been destroyed. The IUCN lists include Black-faced Spoonbill, Great Ibis, Waldrapp Ibis and Oriental Crested Ibis as endangered and Madagascan Crested Ibis as vulnerable.
The differences in their bill shapes reflect their different foraging techniques. Ibises bills are designed for probing into the soft mud in shallow waters whereas Spoonbills are designed to feed by moving their partially open bills from side to side, their bills snap shut very quickly whenever anything solid passes between the two mandibles. Ibises and Spoonbills are carnivorous, primarily tactile hunters, and can feed as well by night as they can by day. Some Ibises will also hunt visually for insects in grasslands. Some species such as Bald, Waldrup and Hadada Ibises are in fact more terrestrial than aquatic though most species are primarily or totally adapted to wetland habitats. The birds use a number of foraging techniques from standing still at the edge of, or in some water waiting to spear a fish, through acts like stirring the water or grass with a foot or flicking the wings, to disturbing or startling prey, to walking rapidly through the environment. Prey flushing actions such as 'Foot Stirring' and 'Wing-flicking' can be used in conjunction with a slow walk or a walk-stop-walk-stop hunting method as well as when standing still.
Most, if not all species are monogamous and nest in colonies, the exception being the Oriental Crested Ibis (Niponnia nippon)which nests in isolated pairs. Many species have crests of erectile feathers on the head which are raised as part of the courtship display. Individual species have a repertoire of behaviours associated with courtship. These are all adapted from defence or preening activities, some examples of this are the Erect Posture display adapted from the Alarm Posture and the Bowing display adapted from an Appeasement display.
Nests are built of vegetable matter, sticks, reeds or vines brought by the male to the site. The female does most of the building. A variable number of eggs, normally about five, are laid and incubated by both sexes. The young are fed regurgitated food which they obtain by sticking their heads down into the parent's gullet to eat. Both parents feed the young and one adult remains at the nest at all times while the young are small. The young cannot stand when first hatched and have short simple bills. These however soon start to take on the adult form.
The Sacred Ibis, Threskiornis aethiopicus, so named because it was revered in ancient Egypt as the symbol of Thoth, the god of writing and wisdom, s perhaps the best known example of a bird being involved in human mythology. Thoth himself is depicted as having an Ibises head, and live Ibises were kept in his temples. Sacred Ibises were also mummified and kept in special animal necropolises, these sites sometimes contained huge numbers of mummified birds, up to half a million in a few cases. Unfortunately its sacred stature did not not protect the Sacred Ibis in Egypt and it is now extinct there, though it occurs in other countries and is common in aviaries.
Checklist of Herons of the World, with numbers of Subspecies, length in cms, weight in gs and a brief note on distribution.
The Storks (Ciconiidae) are the largest of the Ciconiiformes standing 22 to 60 inches or 55 to 150 cms tall. The smallest Stork is the African Openbill Stork which stands 55 to 60 cms tall, several species including the Saddlebill Stork, the Jabiru Stork and the Greater Adjutant Stork can all reach 150 cms in height. Most species are found in Tropical Africa and Asia, though two species occur in Europe and three in Central and South America. Some storks are migratory. The Black Stork migrates from temperate Eurasia to tropical Afro-Asia. Other migratory storks include the White Stork and Oriental White Stork. Storks have a pantropical to warm temperate distribution.
Storks have little or no webbing between their toes and their tibia (upper leg) is bare of feathers. As a family they have 12 primaries, though in some species the 12th is secondarily reduced or absent altogether. They have the delightful habit of defecating on their legs in order to cool them down, evaporative cooling at its smelliest. They also have 12 retrices (tail feathers).
Like their relatives the Ibises and Spoonbills most storks are birds of wetlands, because so much of this habitat has been destroyed world-wide a number of species are endangered and most have declining populations. In the IUCN lists the Greater Adjutant Stork is listed as endangered while Storm's Stork, Lesser Adjutant Stork, Milky Stork, Oriental White stork and Black Stork are all listed as vulnerable.
In Europe, White Storks were once considered to symbolically be responsible for the arrival of babies, and though this idea is not taken seriously the imagery has caught on. Cards designed to be sent to congratulate a couple on the arrival of a new child still often carry the image of a Stork carrying a baby as it flies to deliver it. This imagery has spread from Europe to many parts of the world in the last 50 years.
Storks are highly carnivorous birds feeding on a range of animals from small mammals and birds to reptiles, amphibians, fish and invertebrates. Not all species feed on all these foods, however. Some species are generalists taking whatever is available, while others have very specialist diets. The Openbilled Storks are specialists on aquatic snails and seldom feed on anything else. Adjutant Storks are part-time scavengers at the kills of larger predators though they feed their young only on live caught food.
Storks show a variety of feeding techniques ranging from standing still and waiting for prey items to come along to slowly walking about to actively probing in the water, soil and vegetation. Some storks are mostly visual hunters catching prey on sight while others can hunt tactilely as well (by feel). The American Wood Stork forages just as efficiently in the dark as in the light. Storks may use a number of techniques to help them flush out prey such as wing flicking and stirring with their feet. They will also turn over logs and small stones to find prey beneath.
All storks are socially monogamous, however many species are genetically promiscuous (See Reproductive Strategies in Birds). The true extent to which this promiscuity effects the family is unknown because of the limited amount of DNA testing which has been done. Most Storks nest colonially, a habit which makes seeking extra-pair copulations easy, only the Black Stork nests solitarily. Some species such as the White Stork maintain and renew their pair bond every year, but for others the pair-bond only lasts for a single breeding season. Some species undergo a seasonal change in colour of the bare skin on the head and legs during the breeding season.
Nests of most species are relatively large being built out of various plant material brought to the site by the male who offers the materials to the female. Most nests are built in trees, though some species nest on cliffs and the White Stork has come to nest primarily human buildings, now-a-days these often include specially constructed platforms form them to nest on. The females does most of the actual construction work. A variable number of eggs, usually 3-5, are laid and incubated by both sexes. When the young hatch they are altricial (few feathers and cannot stand). They are fed on regurgitated food vomited up onto the floor of the nest by the adults. While the young are helpless one adult is always near the nest.
Checklist of Herons of the World, with numbers of Subspecies, height in cms, weight in gms and a brief note on distribution.