A study by the Wyoming Cooperative Fish and Wildlife Research Unit shows that elk are not especially stressed out by the presence of wolves.
Pregnancy rates among migratory elk herds near Yellowstone have declined, and one theory was that wolves were harassing the elk – causing them to run and hide, and depriving them of grazing opportunities.
Arthur Middleton, the lead author on the report, says elk did move around somewhat to get away from wolves, but only when the wolves were within one kilometer away. And he says wolves only rarely came that close.
“Does this mean that wolves don’t affect elk? No, it doesn’t mean that. We were looking here at whether there was this added effect that had been suggested: on top of killing elk, do wolves sort of incur these nutritional and reproductive costs? What we’re finding here is that we don’t have that added effect.”
Middleton says drought and direct predation by grizzly bears and wolves account for the decline in elk pregnancies.