A new study from the University of Oxford revealed that the further turtle doves and reed warblers traveled, the more new neurons they had in their brain. Interestingly, however, researchers found the neurons are utilized for different purposes.
Reed warblers have set up a "neighborhood watch" to protect their nests from invasive cuckoos, who lay their eggs in local nests for others to raise. When reed warblers spot a cuckoo, they mob it and emit alarm calls that alert neighbors a cuckoo is at large and they should monitor their eggs closely. This has greatly benefited warblers, but cuckoo populations appear to be suffering.