The wolves that were reintroduced into Yellowstone were of the
sub-species, Canis lupus occidentalis, the largest of the grey
wolf species, which gets nearly 100 lbs. larger than the
original species (canis lupis irremotus). CI irremotus was not
extirpated from the Canadian province of Alberta, so why wasn't
it chosen to replace the original Yellowstone wolves, instead of
the largest sub-species from the Artic regions? The smaller wolf
which was original to that area might have been a much better
choice in the balance between wolf and elk, without as much
damage to the elk herd and surrounding cattle, sheep, etc. Were
they even needed? Some say yes, the elk were overgrazing the
park and becoming sickly. Because of the overgrazing the beaver
were disappearing, not creating the wetlands needed to replenish
the grasses. Enter the coyote, which were also reintroduced and
got out of hand. Perhaps the choice of the larger wolf was to
trim the coyote packs also. The larger CI occidentalis, is
reputed to "kill for sp