Areas in the Wadden Sea, part of the North Sea, where red larks, migratory birds, spend the winter are under pressure. The Wadden Sea is changing due to human influences such as mining, tourism and sea level rise, and red larks create and adapt their behavior according to environmental changes.

Researcher Selin Ersoy, an ecologist at the Royal Netherlands Institute for Marine Research (NIOZ) studied how the personalities of individual red larks differ and affect how they search for food.

Individuals that are fast explorers and take the risk of searching in various areas also eat different types of food. This could cause red larks to become more resilient as their environment changes. These birds may copy the foraging behavior of adventurous peers that manage to survive in new places, according to Science Daily.

“Character differences between red larks seem to be an important ingredient for the resilience of the whole group,” said researcher Selin Ersoy.

Birds also have personality

Red herons of both sexes and all ages show different behavioral traits. These remain unchanged over time, but differ among individuals. Some of them are more adventurous and show braver exploratory behaviors in some environments than others.

Other individuals take less risks and hardly dare to move into a new environment. These “personalities” have ecological and evolutionary consequences, but to what extent is unknown, as few studies have investigated this aspect in the field.

During his PhD research, Selion Ersoy developed a new way to identify personality variations in red larks. Ersoy wanted to find out whether behavior in experimental environments can be extrapolated to a larger and more complex natural environment and how individual differences develop.

“With our new method that allows us to study the personality of animals in the wild, we believe that larks probably develop their personality through the experience they get growing up. After growing up, adults remain with exploratory behaviors. These appear to be character types in humans,” Ersoy said.

Explorers feed on better quality food

Ersoy and his colleagues observed several types of behaviors in the wild. For example, variation in personality type—such as fast or slow explorer—predicts foraging tactics and dietary choice in the wild.

Fast explorers use more visual foraging and eat soft prey such as shrimp or worms, while slow explorers search for prey tactilely and feed on hard-shelled prey such as clams. This is a novel explanation for variation in feeding niche specialization among individuals within the same population.

Exploratory behavior is related to the variation of movements in space and time

Researcher Selin Ersoy stated that the discrepancies observed between fast and slow explorers were also noticed at the level of their deployment in time and space.

“We were amazed to see that slow and fast explorers have distinctly different movement patterns during the night, while during the day they move more or less the same way. These different individuals even have different arrival times from migration. Fast explorers arrive in the Wadden Sea later than slower explorers,” explained ecologist Selin Ersoy.

Ersoy and her colleagues want to further study where the birds stay in the meantime. Perhaps these red larks need more time to care for their young in the Arctic.

The benefits of the whole group

Entire populations of red herons could learn how to diversify their foraging patterns thanks to fast explorers, according to researcher Ersoy.

“We found striking differences in feeding and movement patterns between slow-exploring and fast-exploring red larks. This suggests that fast explorers could provide foraging information and new foraging opportunities for entire populations,” says Ersoy.

Selin Ersoy’s study fills a critical gap between experimental research on wild animals in controlled environments and observed behavior in the wild.

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