Yeah, there’re all these weather changes and destructive elements…for humans, there are wars and diseases. For lemmings…well, there are the suiciding stuff. Alright, kinda tired, gonna take a nap now. Tchao.
Yeah, my mistake about the lemmings. However, after checking up on my wrongness, them drowning in lakes and rivers do regulate their population. The natural diet for lemmings is moss, and as their numbers grow, their food supply grows pretty darn short. So they migrate (lemmings don’t hibernate)- searching for areas where there is moss. When they come across natural barriers, some don’t make it. Thereby Darwin’s Natural Selection- the strong ones survive, the weak ones go “plooop”.