Storks (Family Ciconiidae) - Bird of the Month: March 2013

[Lisbeth]

A woolly-necked stork at Ballito.

[Dewi]

The "Flasher" strikes again.

[Dewi]

A Wooly-necked Stork going to roost on a gnarled old tree.

[leachy]

[Amoli]

The pics of the Wooly neck in flight is great.

I looked up in my bird book to see what the red stripe is in the wing... it doesn't say anything. Anybody know more?

[nan]

Kruger again

Woolly-necked Stork/Cigogne épiscopale

[Lisbeth]

Even the woolly necked storks have learned to beg for food



You cannot see the see the building, but it is right there on the right hand side

[Toko]

White Stork

Description
The White Stork is a large bird. It has a length of 100–115 cm, and a standing height of 100–125 cm. The wingspan is 155–215 cm and its weight is 2.3–4.5 kg. Like all storks, it has long legs, a long neck and a long straight pointed beak. The sexes are identical in appearance, except that males are larger than females on average. The plumage is mainly white with black flight feathers and wing coverts; the black is caused by the pigment melanin. The breast feathers are long and shaggy forming a ruff which is used in some courtship displays. The irises are dull brown or grey, and the peri-orbital skin is black. The adult has a bright red beak and red legs, the coloration of which is derived from carotenoids in the diet.
As with other storks, the wings are long and broad enabling the bird to soar. In flapping flight its wingbeats are slow and regular. It flies with its neck stretched forward and with its long legs extended well beyond the end of its short tail. It walks at a slow and steady pace with its neck upstretched. In contrast, it often hunches its head between its shoulders when resting. Moulting has not been extensively studied, but appears to take place throughout the year, with the primary flight feathers replaced over the breeding season.
Upon hatching, the young White Stork is partly covered with short, sparse, whitish down feathers. This early down is replaced about a week later with a denser coat of woolly white down. By three weeks, the young bird acquires black scapulars and flight feathers. On hatching the chick has pinkish legs, which turn to greyish-black as it ages. Its beak is black with a brownish tip. By the time it fledges, the juvenile bird's plumage is similar to that of the adult, though its black feathers are often tinged with brown, and its beak and legs are a duller brownish-red or orange. The beak is typically orange or red with a darker tip. The bills gain the adults' red colour the following summer, although the black tips persist in some individuals. Young storks adopt adult plumage by their second summer.

Distribution and habitat
The nominate race of the White Stork has a wide although disjunct summer range across Europe, clustered in the Iberian Peninsula and North Africa in the west, and much of eastern and central Europe, with 25 percent of the world's population concentrated in Poland, as well as parts of western Asia. The asiatica population of about 1450 birds is restricted to a region in central Asia between the Aral Sea and Xinjiang in western China. The Xinjiang population is believed to have become extinct around 1980. Migration routes extend the range of this species into many parts of Africa and India. Some populations adhere to the eastern migration route, which passes across Israel into eastern and central Africa.
A few records of breeding from South Africa have been known since 1933 at Calitzdorp, and about 10 birds have been known to breed since the 1990s around Bredasdorp. A small population of White Storks winters in India and is thought to derive principally from the C. c. asiatica population as flocks of up to 200 birds have been observed on spring migration in the early 1900s through the Kurram Valley. However, birds ringed in Germany have been recovered in western (Bikaner) and southern (Tirunelveli) India. An atypical specimen with red orbital skin, a feature of the Oriental White Stork, has been recorded[38] and further study of the Indian population is required. North of the breeding range, it is a passage migrant or vagrant in Finland, Great Britain, Iceland, Ireland, Norway and Sweden, and west to the Azores and Madeira. In recent years, the range has expanded into western Russia.
The White Stork's preferred feeding grounds are grassy meadows, farmland and shallow wetlands. It avoids areas overgrown with tall grass and shrub. In parts of Poland, poor natural foraging grounds have forced birds to seek food at rubbish dumps since 1999. White Storks have also been reported foraging in rubbish dumps in the Middle East, North Africa and South Africa.
The White Stork breeds in greater numbers in areas with open grasslands, particularly grassy areas which are wet or periodically flooded, and less in areas with taller vegetation cover such as forest and shrubland. They make use of grasslands, wetlands, and farmland on the wintering grounds in Africa.

Migration
White Storks fly south from their summer breeding grounds in Europe in August and September, heading for Africa. There, they spend the winter in savanna from Kenya and Uganda south to the Cape Province of South Africa. In these areas they congregate in large flocks which may exceed a thousand individuals. Some diverge westwards into western Sudan and Chad, and may reach Nigeria. In spring, the birds return north; they are recorded from Sudan and Egypt from February to April. They arrive back in Europe around late March and April, after an average journey of 49 days. By comparison, the autumn journey is completed in about 26 days. Tailwinds and scarcity of food and water en route (birds fly faster over regions lacking resources) increase average speed.
To avoid a long sea crossing over the Mediterranean, birds from central Europe either follow an eastern migration route by crossing the Bosphorus to Turkey, traversing the Levant, then bypassing the Sahara Desert by following the Nile valley southwards, or follow a western route over the Strait of Gibraltar. These migration corridors maximise help from the thermals and thus save energy. The eastern route is by far the more important with 530,000 White Storks using it annually, making the species the second commonest migrant there (after the European Honey Buzzard). The flocks of migrating raptors, White Storks and Great White Pelicans can stretch for 200 km. The eastern route is twice as long as the western, but storks take the same time to reach the wintering grounds by either.
Juvenile White Storks set off on their first southward migration in an inherited direction but, if displaced from that bearing by weather conditions, they are unable to compensate, and may end up in a new wintering location. Adults can compensate for strong winds and adjust their direction to finish at their normal winter sites, because they are familiar with the location. For the same reason, all spring migrants, even those from displaced wintering locations, can find their way back to the traditional breeding sites.

Energetics
White Storks rely on the uplift of air thermals to soar and glide the long distances of their annual migrations between Europe and Sub-Saharan Africa. For many, the shortest route would take them over the Mediterranean Sea; however, since air thermals do not form over water, they generally detour over land to avoid the trans-Mediterranean flights that would require prolonged energetic wing flapping.[60] It has been estimated that flapping flight metabolises 23 times more body fat than soaring flight per distance travelled. Thus, flocks spiral upwards on rising warm air until they emerge at the top, up to 1200–1500 m above the ground.
Long flights over water may occasionally be undertaken. A young White Stork ringed at the nest in Denmark subsequently appeared in England, where it spent some days before moving on. It was later seen flying over St Mary's, Isles of Scilly, and arrived in a poor condition in Madeira three days later. That island is 500 km from Africa, and twice as far from the European mainland. Migration through the Middle East may be hampered by the khamsin, winds bringing gusty overcast days unsuitable for flying. In these situations, flocks of White Storks sit out the adverse weather on the ground, standing and facing into the wind.

Behaviour
The White Stork is a gregarious bird; flocks of thousands of individuals have been recorded on migration routes and at wintering areas in Africa. Non-breeding birds gather in groups of 40 or 50 during the breeding season. The smaller dark-plumaged Abdim's Stork is often encountered with White Stork flocks in southern Africa. Breeding pairs of White Stork may gather in small groups to hunt, and colony nesting has been recorded in some areas. However, groups among White Stork colonies vary widely in size and the social structure is loosely defined; young breeding storks are often restricted to peripheral nests, while older storks attain higher breeding success while occupying the better quality nests toward the centres of breeding colonies. Social structure and group cohesion is maintained by altruistic behaviours such as allopreening. White Storks exhibit this behaviour exclusively at the nest site. Standing birds preen the heads of sitting birds, sometimes these are parents grooming juveniles, and sometimes juveniles preen each other. Unlike most storks, it never adopts a spread-winged posture, though it is known to droop its wings (holding them away from its body with the primary feathers pointing downwards) when its plumage is wet.
A White Stork's droppings, containing faeces and urine, are sometimes directed onto its own legs, making them appear white. The resulting evaporation provides cooling and is termed urohidrosis. Birds that have been ringed can sometimes be affected by the accumulation of droppings around the ring leading to constriction and leg trauma. The White Stork has also been noted for tool use by squeezing moss in the beak to drip water into the mouths of its chicks.

Communication
The adult White Stork's main sound is noisy bill-clattering, which has been likened to distant machine gun fire. The bird makes these sounds by rapidly opening and closing its beak so that a knocking sound is made each time its beak closes. The clattering is amplified by its throat pouch, which acts as a resonator. Used in a variety of social interactions, bill-clattering generally grows louder the longer it lasts, and takes on distinctive rhythms depending on the situation—for example, slower during copulation and briefer when given as an alarm call. The only vocal sound adult birds generate is a weak barely audible hiss; however, young birds can generate a harsh hiss, various cheeping sounds, and a cat-like mew they use to beg for food. Like the adults, young also clatter their beaks. The up-down display is used for a number of interactions with other members of the species. Here a stork quickly throws its head backwards so that its crown rests on its back before slowly bringing its head and neck forwards again, and this is repeated several times. The display is used as a greeting between birds, post coitus, and also as a threat display. Breeding pairs are territorial over the summer, and use this display, as well as crouching forward with the tails cocked and wings extended.

Feeding
White Storks consume a wide variety of animal prey. They prefer to forage in meadows that are within roughly 5 km of their nest and sites where the vegetation is shorter so that their prey is more accessible. Their diet varies according to season, locality and prey availability. Common food items include insects (primarily beetles, grasshoppers, locusts and crickets), earthworms, reptiles, amphibians, frogs and small mammals such as voles, moles and shrews. Less commonly, they also eat bird eggs and young birds, fish, molluscs, crustaceans and scorpions. They hunt mainly during the day, swallowing small prey whole, but killing and breaking apart larger prey before swallowing.
The diet of non-breeding birds is similar to that of breeding birds, but food items are more often taken from dry areas. White Storks wintering in western India have been observed to follow blackbuck to capture insects disturbed by them. Wintering White Storks in India sometimes forage along with the Woolly-necked Stork. Food piracy has been recorded in India with a rodent captured by a Western Marsh Harrier appropriated by a White Stork, while Montagu's Harrier is known to harass White Storks foraging for voles in some parts of Poland.

Breeding and lifespan
The White Stork breeds in open farmland areas with access to marshy wetlands, building a large stick nest in trees, on buildings, or on purpose-built man-made platforms. Each nest is 1–2 m in depth, 0.8–1.5 m in diameter, and 60–250 kg in weight. Nests are built in loose colonies. Not persecuted as it is viewed as a good omen, it often nests close to human habitation; in southern Europe, nests can be seen on churches and other buildings. The nest is typically used year after year especially by older males. The males arrive earlier in the season and choose the nests. Larger nests are associated with greater numbers of young successfully fledged, and appear to be sought after. Nest change is often related to a change in the pairing and failure to raise young the previous year, and younger birds are more likely to change nesting sites. Although a pair may be found to occupy a nest, partners may change several times during the early stages and breeding activities begin only after a stable pairing is achieved.
Paired birds greet by engaging in up-down and head-shaking crouch displays, and clattering the beak while throwing back the head. Pairs copulate frequently throughout the month before eggs are laid. High-frequency pair copulation is usually associated with sperm competition and high frequency of extra-pair copulation; however, extra-pair copulation is infrequent in White Storks.
A White Stork pair raises a single brood a year. The female typically lays four eggs, though clutches of 1–7 have been recorded. The eggs are white, but often look dirty or yellowish due to a glutinous covering. They measure 72.58 mm × 51.86 mm, and weigh 96–129 g. Incubation begins as soon as the first egg is laid, so the brood hatches asynchronously, beginning 33 to 34 days later. The first hatchling typically has a competitive edge over the others. While stronger chicks are not aggressive towards weaker siblings, as is the case in some species, weak or small chicks are sometimes killed by their parents. This behaviour occurs in times of food shortage to reduce brood size and hence increase the chance of survival of the remaining nestlings. White Stork nestlings do not attack each other, and their parents' method of feeding them (disgorging large amounts of food at once) means that stronger siblings cannot outcompete weaker ones for food directly, hence parental infanticide is an efficient way of reducing brood size. Despite this, this behaviour has not commonly been observed.
The temperature and weather around the time of hatching in spring is important; cool temperatures and wet weather increase chick mortality and reduce breeding success rates. Somewhat unexpectedly, studies have found that later-hatching chicks which successfully reach adulthood produce more chicks than do their earlier-hatching nestmates.[90] The body weight of the chicks increases rapidly in the first few weeks and reaches a plateau of about 3.4 kg in 45 days. The length of the beak increases linearly for about 50 days. Young birds are fed with earthworms and insects, which are regurgitated by the parents onto the floor of the nest. Older chicks reach into the mouths of parents to obtain food. Chicks fledge 58 to 64 days after hatching.
White Storks generally begin breeding when about four years old, although the age of first breeding has been recorded as early as two years and as late as seven years. The oldest known wild White Stork lived for 39 years after being ringed in Switzerland, while captive birds have lived for more than 35 years.

[Amoli]

White stork

[Dewi]

White Storks build some precarious looking nests.



They often breed in loose colonies or singly.



Although they have taken to nesting on man-made structures, the fork of a tree is the more natural location.



After migrating from Africa, males arrive first and await the return of the females.







Established pairs display at the nest site to re-establish the pair bond, whilst first time breeders display together and search out a suitable nest site to start their breeding.



Males bring in nesting material continually.











White Storks lay on average four eggs which are incubated for 33-34 days. Chicks fledge after 58-64 days.