The ones that survived will have had more efficient metabolisms, or harder hooves that could break through the ice to get to the food, or could have learned a technique to cope. Hopefully their next generation will retain those traits or that culture to adapt.
Bigger animals have low numbers, larger ranges, less genetic variability, longer reproductive cycles, evolve much slower, and tend to go extinct much more reliably.
Or they’ll just go extinct. Not all species will adapt.
Yeah, animal species definitely successfully evolve over the course of a dozen years /s
I don't think GP's comment shows the lack of understanding of evolution that you're trying to point out: numerous similar events occurring to a range of herds over a period of time is exactly how that would happen isn't it?
Not to say I agree (or not) this particular case would be effective, or that it's fine for man's influence to cause it, or anything. Just I don't think they showed any sign of thinking caribou would suddenly evolve like a Pokémon to have a stronger hoof or something.
Yeah ... animal (and plant, etc.) populations in a stable environment have a lot of random variations that confer no outright distinct advantages over their peers, they are distributed along the normal plane to the current evolutionary gradient. When environments suddenly change, it's not like animal populations rapidly create new random mutations that confer advantages in subsequent generations. Rather, the new conditions make previously existing traits that some animals within the population had and others didn't have more significant to survival, and so those advantageous traits are emphasized in subsequent generations.
After this "evolutionary bottleneck", other new random mutations / variations will occur generations later that might have no seeming immediate advantage / disadvantage to the "new normal", but at some subsequent change in the environment, the cycle of weeding out "bad" traits will happen again.