Yellowstone's Northern Range - Greater Yellowstone Science ...

ELK POPULATION ISSUES
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It has evolved in the past 20 years to become
Montana's most economically valuable elk herd
(Duffield 1989). Historic developments like this
improvement in cooperation and long-range habitat
protection are models that should be useful for
many other cross-boundary initiatives near
Yellowstone National Park and elsewhere.
Longstanding preconceptions about the
abundance or perceived overabundance of some
wildlife species, and resultant popUlation reduction
programs, have been questioned in the United
States and elsewhere (Houston 1982, Macnab
1991). Wildlife managers now face difficult
questions about "appropriate" levels of abundance
for many popular wildlife species (Garrott et a1.
1993). Due to confusion with commercial
livestock standards, the ecological carrying
capacity of the northern range was underestimated
for many years prior to the early 1970s, and as
additional winter range was made available to the
elk in the 1980s, that calTying capacity increased.
Since the reoccupation of that additional winter
range, the elk population has not increased further,
nor has the density of elk on the park's winter
range increased. Instead it has fluctuated in
response to varying climatic conditions.
The northern Yellowstone elk herd is not
now, and has never been, growing "out of control."
The factors limiting that growth include quality and
quantity of available forage, winter severity,
predation by a variety of large carnivores, and
human hunting north of the park. During the 1970s
and 1980s, as the herd responded to release from
the extreme suppression of the 1960s, it may have
appeared to many observers that it was in fact
growing without any sign of stabilizing, but many
other greater Yellowstone ungulate herds were also
increasing, especially during the easy years of 1980
to 1986, when wet summers and mild winters
fostered population increases.
The natural regulation policy, now almost 30
years in place, has provided Yellowstone National
Park with its foremost opportunity to learn about
the northern range grazing system, but the vast
amount of new information has not led to a
resolution of many of the debates over the northern
range. Natural regulation policy has been criti-
cized for lacking the rigid hypothesis-testing
criteria required of many such experiments. Such
criticisms are easy to make but difficult to back up
with a fundable alternative research approach. The
northern range is a huge, complex wildland
ecosystem still potentially subject to the full range
of climatic, geophysical, and ecological variables it
has experienced since the glaciers retreated more
than 12,000 years ago, as well as to the still poorly
understood influences of humans for almost as
long. Short of an epic science-fiction treatment, it
is impossible to imagine an experimental test
approach broad, comprehensive, and massively
funded enough to fully address all of the hypotheses
either stated or implied in the natural regulation
policy. Indeed, there is considerable disagreement
over what those hypotheses were in the fIrst
place, or should be now. Changes in scientific
understanding of ecosystems have come so fast in
the past 30 years that any such complete set of
hypotheses developed at the initiation of the natural
regulation policy (and dealing not merely with
ungulate-vegetation interactions but with everytiring
else) would in fact be either inadequate or
even obstructive today. This report shows that a
tremendous amount of productive research on the
nOlthern range has successfully addressed many
aspects of natural regUlation, and has made great
progress in clarifying the workings of the northern
range. This report also shows that much more
needs to be done.
For most of this century, the foremost
recommendation regarding the northern range has
been to reduce the number of elk living there.
Similar recommendations have prevailed in other
national parks, most involving elk or white-tailed
deer (Wright 1992, Wagner et. aI1995a). The most
recent generation of science in Yellowstone has
provided abundant cause to question the wisdom of
such reductions. There is ample reason to believe
that ungulates were common in the park area
prehistorically. there are varied carnivore species
whose wellbeing is tied closely to the large herds
of ungUlates, and there is now a considerable
regional economic stake in the existence of a large
migratory northern Yellowstone elk herd.
Porter (1992) is the latest of several authors