Yellowstone National Park Policy: Natural Regulation
What Is Natural Regulation?
Natural regulation is a scientific theory that
describes the process by which wildlife populations fluctuate over
time. Fluctuation in population abundance is attributed
to non-constant birth and death rates, which are affected by a multitude
of factors including, winter severity, forage quantity and quality,
immigration and emigration, hunting and predation by other wildlife. Yellowstone
National Park has adapted natural regulation theory
to management policies, affecting elk within the park.
For a more complete summary of the science
behind natural regulation, the controversy
surrounding natural regulation policy, and interviews
from biological professionals, visit natural
What are the necessary assumptions of Natural
In order for natural regulation to "work", certain
assumptions must be met:
ecosystem must be contained, or function as a complete unit.
flora and fauna components must be represented within the natural
range of ecosystem conditions.
influences on the ecosystem at large must be minimal.
How Does Natural Regulation Affect Elk?
A naturally regulating elk population will exhibit
a lower rate of growth, as the population size gets closer to an
area carrying capacity. Likewise,
as elk population numbers decline, the rate of growth will increase. This cycle is described as a "biofeedback response". Where large numbers of elk are found on the
same rangelands, the average condition of individual elk declines. Condition in this sense implies health, or vigor.
The amount of fat a cow elk carries would be less if that
animal were living on a densely populated rangeland, as opposed
to a sparsely populated rangeland. The relationship between elk condition and population
density has been documented on elk in Yellowstone. On the northern range, declining pregnancy rates
in elk are followed by increasing winter mortality rates of very
young and old elk where population numbers are high.
Climate and predation are also important to balancing of
elk populations under natural regulation.
From 1987-1990, a recorded 33% of newborn elk were lost to
predation by animals such as: bears, coyotes and golden eagles.
Also during this time period, a recorded 20% of the total
elk population died each winter due to limited food resources, most
of which were very young and old animals.
What Is the Alternative to Natural Regulation?
An alternative to using natural regulation theory
to guide elk management in Yellowstone National Park is natural
control. "Natural control" was a management strategy
used previous to natural regulation in Yellowstone. Under natural control, Yellowstone’s previous management objectives
aimed to: "limit park control operations to duplicating the
action of natural predation which relieves severe overuse
of vegetation and reduce extreme fluctuations in animal numbers." Therefore, the park was more actively involved in maintaining elk
at "natural" levels, instead of allowing the natural regulation
of elk to occu
Implementing Natural Regulation:
In the early 1970s, Yellowstone embarked on a new policy
of wildlife management: natural regulation. At this time, Cole
was the superintendent of Yellowstone National Park. Shortly after,
Houston became the new head biologist, and gave complete backing
to policy of natural regulation. By implementing natural regulation
policy, Yellowstone was inferring that no human influences would
intervene to control wildlife. Ungulate populations
in Yellowstone are thought to be self-regulating, which
allowed the park to comfortably adopt natural regulation as a wildlife
Landscape Requirements for Natural Regulation:
Wildlife can only self-regulate in the context of a complete ecosystem,
under the theory of Natural Regulation. Yellowstone National Park
is not a complete ecosystem, and in fact elk herds, which summer
in Yellowstone, have most or part of their winter ranges outside
of the park. However, in the area immediately surrounding the park,
a lot of National Forest lands, BLM, and a National Refuge (the
National Elk Refuge), create a more continuous landscape. To the
north, the Gallatin National Forest fosters winter rangelands for
the migrating Northern Range and Gallatin elk herds. To the south,
Grand Teton National Park and the National Elk Refuge provide wintering
range for the Jackson herd. The Shoshone National Forest provides
winter range for both the Carter Mountain herd and the North Fork
Shoshone Herd. The Targhee National Forest is home to the Sand
Creek herd in the winter, and to a lesser extent, the Madison-Firehole
Herd. Although the landscape is fairly continuous, with the exception
of road systems, intermingled towns and private land, the policy
surrounding wildlife management is dramatically different depending
on the landownership involved. It is hard to know if Natural Regulation
is an adequate wildlife policy for Yellowstone National Park, because
the same elk herds, which are self-regulating on Yellowstone
property, are being hunted, fed, and influenced by humans in various
ways when they cross park boundaries. The assumption that Yellowstone
is a complete ecosystem is not correct in this instance, not necessarily
because of inadequate land base surrounding the park, but because
of conflicting management policy.
Elk Management Policy in Regions Surrounding Yellowstone:
Ranches and amenity homes occur just outside the western
border of Yellowstone National Park
|The management of elk in regions surrounding Yellowstone ranges
from winter feed programs on the National Elk Refuge in Jackson,
Wyoming, to elk hunting on National Forest and BLM lands, to
ranching interaction on private lands. For a review of the
USFS and BLM mission and elk management summaries, visit Other
Federal Agencies. For a review of issues surrounding
elk and ranching interest interaction, visit, Ranchers".
The main point is that Yellowstone National Park is not an island,
capable of implementing natural regulation policy at the ecosystem
scale. Interagency cooperation and planning is needed to link
the continuous landscape to more continuous policy. Some interagency
cooperation is occurring in Yellowstone. For example, interagency
teams exist to promote support between landowners including:
federal, state, tribal, private ownership, for grizzly bear
management, the northern range fauna (elk a major component),
and bison-Brucellosis. These teams can hopefully overcome some
of the issues wildlife face when inhabiting a multi-agency landscape