Red Knot have distinct characters and food preferences that are formed in the first year of life, according to researchers.
Selin Ersoy, from the University of Groningen, and colleagues investigated the development of character types in the wader using a computer algorithm.
Knot were trapped in the Wadden Sea in the autumn after arriving from their tundra breeding grounds. After blood tests were taken to determine diet, the birds were placed briefly in a tent with sand trays and their movements logged by a camera.
The early experiences of a Red Knot will determine whether it becomes 'passive' or 'exploratory' (Damian Money).
Automatic analysis of the footage unpicked the birds' movements around the tent. This revealed distinct character traits between birds, with some 'exploratory' individuals covering as much as 200 metres within 20 minutes and 'passive' knots sticking to one tray until they were released.
Allert Bijleveld, behavioural ecologisty and the test's creator, said: "This automatic test has proven to be a reliable way to investigate the characters of the knots.
"When we put adult birds in the tent at intervals of days, weeks, and months, the computer comes to the same conclusion on character. But when we repeatedly subject young birds to the test, they are not yet consistent in their measured character."
Blood tests also made clear that food selection was linked to character, with birds classed as 'passive' shown to have chosen prey items that are easier to find but harder to digest, such as shellfish. On the other hand, 'exploratory' individuals choosing more elusive, high-value food such as shrimp.
Bijleveld said: " From the traces left in the birds' blood by their diet, we could see that the older birds, with a consistent character, are also consistent in their food choice.
"Young birds have a less consistent character and are much more variable in their diet. They seem to experiment by trying different prey, even seaweed."
Ersoy and her team concluded that the personality of a Red Knot is formed in its first year of live, shaped by their early experiences of foraging in the Wadden Sea after migrating from the far north. They seem to maintain their character traits in subsequent years, as adults.
The researchers say their study shows how personality can develop with experience in a wild bird, with knot apparently trying out different feeding techniques which later solidify into consistent individual behaviours.
Bijleveld added: "Apparently, it pays off to specialize over time. In a rapidly changing environment, it will therefore be the young birds that can adapt most easily to a new situation with, for example, very different food."
Reference
Ersoy, S, Beardsworth, C E, Duran, E, van der Meer, M T, Piersma, T, Groothuis, T G and Bijleveld, A I, 2024. Pathway for personality development: juvenile red knots vary more in diet and exploratory behaviour than adults. Animal Behaviour, 208: 31-40. DOI: 10.1016/j.anbehav.2023.11.018
