The Long-Haul Messengers: 15 Fascinating Facts About Storks

1. A stork with a spear through its neck proved that birds migrate.

For centuries, people across Europe wondered where birds disappeared to in winter. Some believed they hibernated in mud at the bottom of lakes or even turned into other species. In 1822, a white stork was shot near the village of Klütz in northern Germany with an 80-centimetre African spear lodged in its neck. It had clearly flown all the way from Africa with the weapon still in place, providing dramatic proof of long-distance migration. The bird, known as the Pfeilstorch or "arrow stork", is preserved at the University of Rostock, and around two dozen similar cases have been recorded since.

2. White storks are almost completely silent.

Adult white storks lack well-developed muscles in their syrinx, the vocal organ of birds, so they can barely make a sound beyond hisses. Instead, they communicate by clattering their bills together loudly, often while throwing their heads back over their bodies. Pairs perform this rattling greeting display when they meet at the nest, and the sound can carry a surprisingly long way.

3. Storks cool down by pooping on their own legs.

On hot days, storks deliberately squirt liquid droppings onto their legs, a behaviour known as urohidrosis. As the liquid evaporates, it draws heat away from blood vessels close to the skin and helps lower the bird's body temperature. This is why many storks appear to have white-streaked legs in summer. New World vultures use exactly the same cooling trick.

4. Storks avoid flying over open sea.

Storks are heavy birds that rely on soaring rather than flapping, riding rising columns of warm air called thermals. Because thermals barely form over water, storks avoid long sea crossings whenever possible. Instead, migrating flocks funnel through narrow land bridges such as the Strait of Gibraltar and the Bosporus in Istanbul. During peak migration, hundreds of thousands of storks pass over these bottlenecks in a matter of weeks.

5. Some storks have given up migration in favour of junk food.

White storks from Spain and Portugal traditionally spent the winter in Africa, south of the Sahara. Over recent decades, however, many have stopped migrating and stay in Iberia all year. GPS tracking studies have shown that these birds feed heavily at open landfill sites, which provide a reliable supply of food scraps through the winter. The rubbish dumps have changed the migration habits of an entire population.

6. Young storks migrate without their parents.

Juvenile white storks do not learn the route by following their mothers and fathers. Young birds usually set off on their first migration independently, guided by instinct and by joining flocks of other storks along the way. Many first-year birds then stay in Africa for several years and only return to Europe to breed when they are about three or four years old.

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7. Some storks are leaders and others are freeloaders.

A 2018 study by researchers from the Max Planck Institute of Animal Behavior fitted dozens of young storks with high-resolution GPS trackers. They found that some birds acted as leaders, finding and using thermals efficiently, while others followed and relied on them. The followers had to flap more and spent more energy. They also tended to cut their migration short and spend the winter closer to Europe.

8. Their nests can be used for decades.

White storks often return to the same nest year after year and add new material each season. Over time, a nest on a rooftop, chimney or church tower can grow to more than two metres across and weigh hundreds of kilograms. Some nests in European villages have been occupied by successive generations of storks for decades, and many towns have installed special platforms to protect roofs and power lines.

9. Stork nests are home to uninvited lodgers.

The base of a large stork nest offers shelter to smaller birds. House sparrows, tree sparrows and starlings often build their own nests in the gaps between the stork's sticks. The tiny lodgers benefit from the protection of the much larger birds above them, which generally ignore their noisy neighbours.

10. Stork parents sometimes throw their own chicks out of the nest.

When food is scarce, white storks may eject the weakest chick from the nest. It seems cruel, but it allows the parents to concentrate limited food on the chicks with the best chance of survival. The behaviour has been captured several times on live nest webcams, often to the shock of viewers.

11. The baby-delivering stork has roots in European folklore.

The idea that storks bring babies is centuries old in northern and central Europe. One popular theory links it to the stork's return in spring, roughly nine months after traditional midsummer weddings and festivities. Storks nesting on houses were also seen as a sign of good fortune and fertility. The legend was popularised worldwide in the 19th century, partly through Hans Christian Andersen's fairy tale "The Storks".

12. About one in every four of the world's white storks breeds in Poland.

Poland has the largest breeding population of white storks in the world, with tens of thousands of pairs. Around a fifth to a quarter of the global population nests there, mostly in villages surrounded by wet meadows. The bird is so loved that many Polish villages hold stork festivals, and some keep count of how many pairs return each spring.

13. The marabou stork is nicknamed the undertaker bird.

The African marabou stork has a bald head, a hunched posture and dark wings that resemble a cloak, earning it the nickname "undertaker bird". It has one of the largest wingspans of any land bird, reaching up to around 3.2 metres. Marabous often scavenge alongside vultures and also have a strange inflatable pouch hanging from their throat, which is thought to play a role in social displays.

14. The shoebill is not actually a stork.

The shoebill of East Africa's swamps was long known as the whale-headed stork and was once classified with true storks. Genetic and anatomical studies later showed that it belongs to its own family and is more closely related to pelicans. Its massive shoe-shaped bill is perfect for catching lungfish, and like storks, it clatters its bill to communicate.

15. Storks fly with their necks stretched out.

An easy way to tell a stork from a heron in flight is to look at its neck. Storks fly with their necks fully extended, while herons fold their necks back into an S shape. Storks also have long, broad wings with "fingers" of separated feathers at the tips, which help them soar for hours with barely a single wingbeat.