14 January 2014

Stork Talk

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
Alcalá now has three resident pairs, whose nests can be seen on pylons to the left of the A375 as you come into town from junction 42 on the A381.  You can often see them grazing in the fields nearby, or wheeling overhead.  Further south on the A381 towards Los Barrios there are nests on every pylon, and the derelict sugar factory at El Portal is a veritable housing estate.  The nests are huge and straggly, often home to many smaller birds, and somehow manage to survive the fiercest of winds.

"Stork City" - the old sugar factory at El Portal near Jerez
Each year storks head in their thousands to the former lagoon known as La Janda, southwest of Alcalá, where they enjoy snacking on the freshwater crayfish found its drainage ditches.  It is thought to be the pigment from these which gives the stork's legs and beak their bright red colour.

La Janda suchi bar
Stork facts:

  • 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.
  • Black stork
  • 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.


Alcalabirder said...

An interesting post, Claire. Black Storks are regular over the village during migration usually in small numbers although I've seen a flock of 126 birds. The European and Spanish population is increasing - currently there are just under 400 pairs in Spain (mainly in the western mountains). Small numbers also winter on la Janda and elsewhere

mickbullen said...

Hello Claire. We're coming to stay in Alcala at Antigua Fonda, from 21st March for 10 days and have been in touch with John Cantelo; really enjoying reading your blog!

Claire Lloyd said...

Thanks, look forward to meeting you while you're here!

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