EXTRACTS ON AREAS WITH ALL LARGE NATIVE VERTEBRATE PREDATORS AND THE FULL TROPHIC LADDER BACK TO THE PLEXUS
TAKEN FROM PUBLICATIONS SUBMITTED OR IN PREPARATION, BY BRUCE G. MARCOT AND
COLLEAGUES, INTERIOR COLUMBIA BASIN ECOSYSTEM MANAGEMENT PROJECT, USDA FOREST
SERVICE AND USDI BUREAU OF LAND MANAGEMENT
Bruce G. Marcot
8 September 1997
(note: not included in these extracts are tables, figures, and references; these can be found in the original documents)
Marcot, B. G., M. Castellano, J. Christy, L. Croft, J. Lehmkuhl, R. Naney, R. Rosentreter, R. Sandquist,
and E. Zieroth. In press. Terrestrial ecology assessment. Pp. xxx-xxx in T. M. Quigley and S. J.
Arbelbide, eds. An assessment of ecosystem components in the interior Columbia Basin and portions of the
Klamath and Great Basins. USDA Forest Service General Technical Report PNW-xxx. USDA Forest
Service Pacific Northwest Research Station, Portland, OR. xxx pp.
Areas Containing Populations of Large, Wide-Ranging Carnivores
The overall distribution of most of the large carnivores (secondary predators, or tertiary consumers) has declined
and individual populations have decreased since European settlement in the Basin and other parts of the western
The United States. Large carnivores of the ICBEMP assessment area include six species: grizzly bear, American black
bear, gray wolf, mountain lion, lynx, and wolverine (a mid-size carnivore also considered here). All of these are
large-bodied and have large home ranges.
Many parts of the assessment area continue to support populations of black bear and mountain lion but few areas
still contain grizzly bear and gray wolf. Information on distribution and density of wolverine in the assessment area
is lacking, although some studies have been conducted in the Sawtooth Mountains of Idaho. Four areas, the
Yellowstone, North Cascades, Cabinet-Yaak, and Selkirks Grizzly Bear Recovery Areas, each contain all of the six
species but have low numbers of either grizzly bear, wolf, and/or wolverine. Only the Northern Continental Divide
Grizzly Bear Recovery Area (which includes Glacier National Park, the Bob Marshall Wilderness, and the North
Fork of the Flathead River) and possibly parts of the Cabinet Mountains contain populations of all six species that
are well distributed and abundant enough to allow studies to investigate the relations among the above species.
Historically, much of the assessment area, especially the forested parts, supported populations of all of these large
Mountain lions remain well distributed within the forested habitats in the assessment area. Human encounters
with mountain, lions have increased over the past few years, possibly as a result of increased numbers of mountain
lions or of increased human activity in mountain lion habitat. Black bears are also well distributed in the forested
ecosystems within the assessment area. All states continue to offer sport hunting of black bears and most, if not
all, offer permits for mountain lions.
Within suitable vegetation cover types in the assessment area, lynx and wolverine are widely distributed although
their total numbers and local density have been reduced significantly. Within the assessment area, lynx are on the
the southern extension of their range (Koehler and Aubry 1994). Their distribution in the assessment area may have
retracted northward (Koehler and Aubry 1994). The largest concentration of lynx in the contiguous 48 states has
been identified in north-central Washington (Brittell and others 1989). Smaller, isolated populations remain
across northern Washington but in some cases in very low numbers as compared to historic levels. Most of these
individuals are connected to populations and habitats in British Columbia. Lynx are also present in Idaho and
Montana and are still trapped (two permits per year) in Montana. Wolverine is reported over much of the
assessment area, but are found in very low densities except in parts of the Rocky Mountains (Banci 1994).
The northern Rocky Mountains (Glacier National Park and adjacent wilderness areas) and Yellowstone National
Park has succeeded in maintaining grizzly bear populations because of associations with protected recovery areas
and protection against trapping, poisoning, and killing during the settlement of the western United States. Although
gray wolves were nearly extirpated from all of the lower 48 states, recolonization of the Northern Rocky Mountains
began when the Canadian government relaxed their predator control programs for wolves allowing wolf
populations to expand and disperse southward from Canada (Fritts and others 1994). Changes in human attitudes
toward wolves and reintroducing wolves increase the chances of survival of some of the dispersing animals.
Grizzly bears are present in five of the six currently designated Grizzly Bear Recovery Areas (the Bitterroot
Recovery Area is the exception). The North Continental Divide and Yellowstone Recovery Areas have a grizzly bear
populations that are of sufficient size to study relations and interactions with other species such as predators and
scavengers. The Yellowstone Recovery Area may not have populations of gray wolves (reintroduced in 1995) or
lynx of sufficient size to investigate interactions between species. The Cabinet-Yaak Recovery Area may have
sufficient populations, although the grizzly bear population is still being augmented, of all six predators to warrant
studies of their interactions but no such research is currently being conducted.
There are ongoing studies in northern Montana on grizzly bears, gray wolves, and mountain lions. Some
preliminary anecdotal information from these studies relates to how these three species interact. There have been
four reported cases of wolves killing mountain lions but not consuming them. There has been one report of several
wolves pursuing a grizzly bear sow with a cub and possibly killing and consuming the cub. Other reports are of
wolves killing coyotes.
In previous studies, mountain lions tended to remain with their kill, primarily ungulates, for more than one week
until they eventually completely consumed the animal. In northern Montana, however, mountain lions tend to
abandon their prey following the kill and a single meal. Such observations suggest that other scavengers, such as
magpies and ravens have a continuous source of carrion when such carnivores are present (see footnote 19).
There is speculation (see footnote 19) that mountain lions began to occupy low elevation areas where wolves were
eliminated and took advantage of prey sources. With the recovery of wolves and their occupation of low elevation
valleys, mountain lions will likely recede to their more traditional habitat of rougher terrain.
Paquet (1992) indicated that where prey resources are not limiting, that is where healthy populations of deer,
moose and elk are present, little competition for food occurs among large carnivores. Paquet (1992) found that
where coyotes and wolves occupied the same area, and elk, white-tailed deer, and moose were present, coyotes
tended to prey primarily on deer and occasionally on young elk, and wolves selected elk and white-tailed deer and,
secondarily, moose. Coyotes also tended to follow wolves to scavenge wolf kills. Periodically, wolves killed
coyotes, but did not search them out. Similar differences in prey preference have been noted in northern Montana
where mountain lions prey more on elk, wolves on deer, and grizzly bears on moose calves. Wolverines are
primarily scavengers (Banci 1994) and benefit from ungulate kill made by other predators. Recent (1995)
information from Yellowstone National Park on reintroduced wolves indicates that grizzly bears are displacing
wolves from carcasses.
Large carnivores can also influence their environment in other ways. Grizzly bear digs in alpine meadows
currently are being investigated relative to nutrient cycling. Preliminary results indicate higher levels of nitrogen
in digs as compared to similar areas with no recent digs. Some plants, especially glacial lily, are more robust and
vigorous within digs.
The distribution and abundance of most of the large-bodied carnivores in the assessment area have decreased since
settlement by Europeans. Very few studies have evaluated the effects of changes in distribution and abundance of
these large animals on other species or the environment. This change, in turn, has likely influenced the
distribution and abundance of scavenger species of vertebrates throughout the assessment area. It is very little
information that suggests populations of prey, particularly ungulates, have increased as a result of the reduction of
predator abundance and distribution. Many ungulate populations, such as deer and elk, have dramatically
increased since declining of predators, but this is largely a result of habitat enhancement or regulation of hunting.
Other potential effects of the long-term decrease in large carnivores might include reduced competition with other
smaller predators, such as coyotes, raccoons, and skunks which allows those species to increase in distribution and
Ultimately, the distribution and health of large carnivore populations of the assessment area can be thought of as
an index of the status and distribution of wild areas in the Western United States. These species are sensitive
indicators of the degree of human-caused change of wildlands. From a human perspective, they also play critical
roles in American Indian Tribal lore and religion and are living embodiments of places that are felt to be still truly
Part II: Extracts from:
Marcot, B. G., L. K. Croft, J. F. Lehmkuhl, R. H. Naney, C. G. Niwa, W. R. Owen, and R. E. Sandquist. In
press. Macroecology, paleoecology, and ecological integrity of terrestrial species and communities of the
interior Columbia River Basin and portions of the Klamath and Great Basins. General Technical Report
PNW-GTR-XXX. USDA Forest Service. XXX pp.
Full Trophic Ladder Component
[under the section on mapping ecological integrity components of terrestrial species and communities]
Component (3h): Vertebrate carnivores--Eight wide-ranging vertebrate carnivores occur in the basin assessment
area: grizzly bear (Ursus arctos), black bear (U. americanus), gray wolf (Canis lupus), cougar (Felis concolor),
lynx (Lynx lynx), wolverine, fisher (Martes pennanti), and American marten (M. Americana). Four of these
species were mapped and are included in this component (fig. 61). The full set of vertebrate carnivores--and by
inference, the full trophic ladder--once likely ranged throughout the entire basin assessment area, but now is
present only in the northern Rocky Mountains, including Glacier National Park, Yellowstone National Park and
adjacent lands, and in other locations where grizzly bear and gray wolf recovery areas overlap, as in central Idaho
and north-central Washington. The database and map for this component show number of species by 4th code
HUC (fig. 61).
The overall map for goal 3, managing for multiple ecological domains and evolutionary timeframes, is shown in
figure 64. HUCs with higher percentage values in this map represent locations with greater occurrences of unique
vertebrate assemblages, and locations with large carnivores (that is, the full trophic ladder). About one-third of the
HUCs ranked moderate (> 20 percent mean condition) for goal 3, and none ranked high. This is not surprising, as
most of the components for this goal do not overlap, by definition of unique geographic assemblages of species.
Locations with moderately scored HUCs include northwestern Montana, the Greater Yellowstone Ecosystem in
western Wyoming, the Cascades Range in north-central Washington, the Columbia River Gorge, and much of the
Klamath Basin-northern Great Basin-Owyhee Uplands along with southern Oregon and Idaho. Collectively, these areas
cover some of the margins of the basin assessment area where unique vertebrate assemblages would be expected to
be found in such "land-locked" geography.