Homing pigeons as a model for the influence of experience on brain composition-including considerations on evolutionary theory.

The brain of homing pigeons seems to be functionally adapted to homing with e.g., larger hippocampi and olfactory bulbs. Furthermore, functional lateralization occurs as well in homing pigeons. Recently, the investigation of the influence of navigational experience on brain composition and lateralization revealed larger hippocampi in homing pigeons with navigational experience compared to inexperienced homing pigeons. Additionally, there are several brain structures in homing pigeons that show a volumetrical lateralization, whereas homing pigeons with navigational experience show a more lateralized brain than pigeons without navigational experience. This gives more insights in the neuronal basis of orientation and brain development in general but demonstrates as well its complexity. Plasticity and lateralization are much more correlated with individual life history than assumed up to date and have to be more considered in comparative research of evolution.