In any group of red knots, respective individuals exhibit a remarkable array of distinct character types. Birds with an exploratory character are motivated to investigate their environment and readily explore unfamiliar areas. Meanwhile, birds with inactive character types are content to remain in familiar territory. Interestingly, the birds do not appear to hatch with predetermined character types. Their characters are formed later, in the first year of life, as a result of their experiences in the Wadden Sea.

According to the researchers, character is also related to food choice. Exploratory types are constantly looking for the best food: prey which are easy to digest. 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. Based on the results of their character assays, the character of the red knot is formed in the first year of life. When they return to the Wadden Sea in subsequent years, they have seemingly formed food preferences and developed their character accordingly.

This research is another step forward in assembling the complex puzzle of wader behaviour. "It is fascinating to see how young birds still react flexibly to their environment and older birds have more fixed patterns. How this fits into a broader evolutionary picture, in terms of flexibility to a changing environment, is an open but interesting question. 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.