Kraus, R. H. S.; Figuerola, J.; Klug, K.: No genetic structure in a mixed flock of migratory and non-migratory Mallards. Journal of Ornithology 157 (3), pp. 919 - 922 (2016)
Scientists studying a rare population of tool-using chimpanzees have found that aging can have a profound impact on their abilities—but not all chimps decline equally.