If a trait exists in a species that makes it more likely to be killed by a predator then that trait will slowly be eliminated in the population. Those that do not possess the trait will breed more thanks to higher rate of survival.

We’ve seen this play out in most deer and elk populations throughout the western US. Having larger and more unique antlers made it much more likely the animal would be killed by hunters versus an animal with genetically smaller antlers. Therefore, the smaller antler buck/elk has more mating opportunities due to longer life — making it much more likely the population will have smaller antlers than big.

Feels like unnatural natural selection, but that really is happening.