Younger storks choose migration routes that are social hotspots

The elegant white stork, known for its long legs and large wings, offers one of the most spectacular views of animal migration. These birds, which travel from Europe to Africa each autumn and return in the spring, form visible flocks that herald the change of seasons. 

A recent study led by the Max Planck Institute of Animal Behavior in Konstanz, Germany, has shed light on why these storks migrate in such groups: they seem to actively choose to fly together. 

Storks prefer routes frequented by their peers

By tracking 158 storks, the experts found the first concrete evidence of this social behavior during migration, revealing that storks prefer routes frequented by their peers, especially when they are young.

“It’s exciting to see the first clues that storks are actually choosing to fly with others,” said lead author Hester Brønnvik, a doctoral student at Max Planck. “But as they gain migration experience, they also gain the independence to ignore social influences.”

“We can all see that storks fly in flocks, but this observation alone never told us whether or not storks are choosing the routes they take in order to migrate with others,” she added. “It could be that storks are selecting their routes based on other criteria – like good winds or a particular destination – that happen to put them in the same place.”

Stork motivation for migration route selection 

To explore the storks’ motivations for route selection, the team utilized a decade’s worth of precise GPS tracking data from storks in southern Germany. This data covered the full migratory journeys of these birds, from inexperienced juveniles to seasoned adults. 

“We could see the complete migrations that these storks took every year for their entire lives, from a three-month-old juvenile on its first migration to a highly experienced nine-year old taking one of its last flights,” Brønnvik explained.

Social dynamics of stork migration 

To better understand the social dynamics characterizing the 158 storks during their migrations, the experts used data from an extended sample of 400 storks. This larger dataset helped them estimate the probable locations of flocks within the migration landscape.

“This doesn’t tell us definitively whether storks flew with others,” Brønnvik said. “Rather, it gives us a probability, telling us whether a stork’s route would likely put it in the path of other storks.” 

With these estimates, the researchers then employed a statistical model to analyze the chosen migration paths of the storks compared to alternative routes that were also available but not taken. This approach allowed the team to infer the reasons behind the storks’ route selections, shedding light on their migratory behavior. “The model basically asked them why they chose the route that they did,” Brønnvik explained. 

Older storks are more willing to fly solo

The analysis revealed that storks of all ages preferred routes with higher concentrations of other storks, though older, more experienced birds showed a decreased preference for such routes, indicating a greater willingness to fly solo if the conditions were favorable.

According to senior author Andrea Flack, the leader of the Collective Migration group at Max Planck, younger storks might rely more on the flock for survival strategies, such as locating thermals – updrafts essential for flight – or finding food during stops. 

“Following others could help you find these essential resources faster,” she said. However, as storks become more experienced, they rely less on this group information, potentially allowing them to better time their migrations for breeding and other individual needs.

These findings  provide insight into the decision-making processes of migrating storks while highlighting the significance of collective behavior in these decisions. 

“Ultimately, we want to know how the decisions of migrating storks are affected by those around them. Our study provides the first clue of just how important the collective is to those decisions,” Flack concluded.

More about storks

Storks are quite fascinating birds, known not only for their distinctive appearance but also for their interesting behaviors and roles in various cultures. 

Migration patterns 

Many stork species are migratory, with some species, like the white stork, known for their impressive migratory journeys. They travel thousands of miles between Europe and Africa, crossing the Mediterranean Sea and the Sahara Desert.

Symbolism and folklore

Storks are famous in folklore, particularly in European cultures, where they are often associated with delivering babies. This myth possibly stems from their habit of nesting on rooftops and in chimneys, making them a close presence in human lives.

Diet and hunting

Storks have a varied diet that includes insects, fish, amphibians, reptiles, small mammals, and even other birds. They are excellent hunters, using their long beaks to snatch up prey.

Nesting habits

Storks are known for building large nests, which they often use for many years. Some nests have been continuously inhabited by successive stork generations for over a century. These nests can be massive, sometimes as large as a small car.

Communication

Unlike many birds, storks are mostly silent since they lack the typical vocal organs to produce songs. Instead, they communicate through bill-clattering, which involves rapidly snapping their bills to make a loud noise that can be heard over long distances.

Longevity and fidelity

Storks can live for 20 to 30 years in the wild. They are also known for their strong pair bonds; many species of storks mate for life, returning to the same partner and nest each breeding season.

Conservation success

The white stork, in particular, has been a conservation success story in many parts of Europe, where populations have rebounded thanks to efforts to preserve their habitats and reduce hunting.

Physical adaptations

Storks are equipped with long legs and necks, which help them wade through shallow waters while looking for food. Their legs have adaptations that allow them to shut off blood flow to prevent heat loss while standing in cold water.

The study is published in the journal Current Biology.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–