One of the most impressive large birds seen regularly around Alcalá is the white stork, Ciconia ciconia. The other day we witnessed about two hundred of them flying overhead, on their way from wintering in Africa to their breeding grounds in Europe. They take the shortest route across the Mediterranean, because the thermals which lift them high into the air during their migration don't form over water. An estimated eighty thousand of them come our way, across the Strait of Gibraltar, though many more cross at the other end of the Med, across the Bosphorus and up through Turkey.
|White storks grazing in the spring meadows|
|"Stork City" - the old sugar factory at El Portal near Jerez|
|La Janda suchi bar|
- Storks communicate by clattering their beaks rather than calling. The sound is amplified by the throat pouch, which acts as a resonator. They also use an up-down display which involves throwing the head backwards and bringing it slowly forwards again; this display serves various purposes, including greetings and threats.
- They measure over a metre from beak-tip to tail, and their wingspan can be as much as 2 metres (6'6"). Males are slightly larger than females, but their plumage is identical.
- They are carnivorous, and eat insects, fish, amphibians, reptiles, small mammals and even small birds. They feed mainly on the ground, among low vegetation, and from shallow water.
- They they don't mate for life, but they do practice 'serial monogamy'. The male usually comes back to the nest to do a bit of repair work before his partner arrives. Both parents incubate the eggs and feed the chicks.
- Juveniles follow their parents on their first migration south, but if they get blown off course they may end up with a different winter location. However, they manage to find their way back to the same nesting sites.
- Storks use the minimum of energy while flying, preferring to glide on thermals with just the occasional wingflap. They can get as high as 1500m and travel as much as 500 km in a day.
- Black storks, Ciconia nigra, also use the Strait of Gibraltar during migration but they are much rarer and very few pairs stay to breed in Spain. They are slightly smaller than white storks, and much more wary of humans.
- Storks have been known to squeeze moss in their beak to drip water into their chicks' mouths.
- They are social birds and bond with each other by mutual grooming, usually with a standing bird grooming the head of a seated one. This serves the additional purpose of helping to keep down the large number of parasites that live in their feathers.
- Storks can live for over 30 years, and don't usually breed until their fourth year.
- Although traditionally migratory, an increasing number of white storks now stay in Spain all year round. This is thought to be because they have learned to find food on rubbish tips, rather than the result of climate change.
- Storks are traditionally associated with fertility, probably because they arrive in the spring. The legend that storks bring babies probably originated in central Europe. It was popularised in a 19th century fairytale by Hans Christian Andersen and is now found all over the world. In Spain, they believe the storks bring the babies from Paris.