Brain size and the risk of getting shot.

Hunting kills hundreds of millions of animals annually, potentially constituting an important selection pressure on hunted species. We hypothesized that hunted individuals differing from survivors by having better ability to distinguish between dangerous humans and other human beings would be at a selective advantage. We tested whether shot individual birds had smaller brains than survivors, under the assumption that individuals with larger brains had superior escape ability. We used a large database on birds from Denmark to test whether getting shot was predicted by brain mass, while controlling statistically for the potentially confounding effects of age, sex, body mass and body condition. Analyses based on all species, or only species that were hunted, while controlling for differences in sampling effort in random effects models, showed consistently that shot individuals had smaller brains than survivors.