Have you ever thought, what came first, the chicken or egg? They both need each other to exist but which happened first? Questions about how things came to be are hard to answer, but questions scientists have been asking for hundreds of years. Scientists have spent lots of time thinking about other traits in birds and how they came to be. As birds change over hundreds of years they can have new traits that differ from one another, we often call this evolution. Woodpeckers are one example of this as they have learned to eat food differently. Some evolved to eat larva that are buried deep in trees, we can call this extractive foraging. They have also evolved to have different brain sizes. Scientists believe these two traits may be connected.
A big question being asked about woodpeckers is what came first; extractive foraging, or big brains. But why do woodpeckers need big brains to pull larva out of trees? Possibly because it is very difficult, as it requires a lot of motor skills, as they must drill away at the tree with their beak to get the larva. Scientists know that animals need a larger brain in order to foraging for food in places that are inaccessible, because bigger brains allow them to be smarter and learn how to get the inaccessible food. In comparison to other birds, woodpeckers have bigger brains, so scientists wanted to answer the question if the larger brain evolved before the extraction behavior, or if the brain became bigger as they learned the behavior?
In order to answer this question, first they needed to know if only bigger brained woodpeckers could extract larva or if smaller ones could. To figure that out they measured how big their brains were, then watched their behaviors to see if the birds with the big brains were the only ones able to extract larva from deep in the tree or were there also woodpeckers with smaller brains that were able to do the same behavior. They found that it was only the woodpeckers with big brains that were extracting the larva from deep in the tree. Meaning their big brain made them smarter!
Next the scientists need to figure out what caused this? Did they grow bigger brains because they needed to be able to extract the larva or are they able to extract the larva because they have big brains. After looking at the history of woodpeckers they realized that the bigger brains evolved and existed before the behavior. This all means that the brain became bigger before they were able to get larva by extracting it from trees, the ones who learned this behavior were only able to because they had bigger brains. Brain size really does make a difference! What could you do with a bigger brain?
References:
Cárdenas-Posada, G., Iwaniuk, A. N., & Fuxjager, M. J. (2023). Extractive foraging behaviour in woodpeckers evolves in species that retain a large ancestral brain. Animal Behaviour, 198, 141–152. https://doi.org/10.1016/j.anbehav.2023.02.003
