Geology topics

Daniel P. Reinhart

Publications and source records attributed to Daniel P. Reinhart.

5 recordsLinked to original sources

USGS2005

Changing numbers of spawning cutthroat trout in tributary streams of Yellowstone Lake and estimates of grizzly bears visiting streams from DNA

Spawning Yellowstone cutthroat trout ( Oncorhynchus clarki ) provide a source of highly digestible energy for grizzly bears ( Ursus arctos ) that visit tributary streams to Yellowstone Lake during the spring and early summer. During 1985–87, research documented grizzly bears fishing on 61% of the 124 tributary streams to the lake. Using track measurements, it was estimated that a minimum of 44 grizzly bears fished those streams annually. During 1994, non-native lake trout ( Salvelinus namaycush ) were discovered in Yellowstone Lake. Lake trout are efficient predators and have the potential to reduce the native cutthroat population and negatively impact terrestrial predators that use cutthroat trout as a food resource. In 1997, we began sampling a subset of streams ( n = 25) from areas of Yellowstone Lake surveyed during the previous study to determine if changes in spawner numbers or bear use had occurred. Comparisons of peak numbers and duration suggested a considerable decline between study periods in streams in the West Thumb area of the lake. The apparent decline may be due to predation by lake trout. Indices of bear use also declined on West Thumb area streams. We used DNA from hair collected near spawning streams to estimate the minimum number of bears visiting the vicinity of spawning streams. Seventy-four individual bears were identified from 429 hair samples. The annual number of individuals detected ranged from 15 in 1997 to 33 in 2000. Seventy percent of genotypes identified were represented by more than 1 sample, but only 31% of bears were documented more than 1 year of the study. Sixty-two (84%) bears were only documented in 1 segment of the lake, whereas 12 (16%) were found in 2–3 lake segments. Twenty-seven bears were identified from hair collected at multiple streams. One bear was identified on 6 streams in 2 segments of the lake and during 3 years of the study. We used encounter histories derived from DNA and the Jolly-Seber procedure in Program MARK to produce annual estimates of grizzly bears visiting streams. Approximately 68 grizzly bears visited the vicinity of cutthroat trout spawning streams annually. Thus, approximately 14–21% of grizzly bears in the Greater Yellowstone Ecosystem (GYE) may have used this threatened food resource annually. Yellowstone National Park (YNP) is attempting to control the lake trout population in Yellowstone Lake; our results underscore the importance of that effort to grizzly bears.

Wyoming↗

USGS2001

Effects of exotic species on Yellowstone's grizzly bears

Humans have affected grizzly bears ( Ursus arctos horribilis ) by direct mortality, competition for space and resources, and introduction of exotic species. Exotic organisms that have affected grizzly bears in the Greater Yellowstone Area include common dandelion ( Taraxacum officinale ), nonnative clovers ( Trifolium spp.), domesticated livestock, bovine brucellosis ( Brucella abortus ), lake trout ( Salvelinus namaycush ), and white pine blister rust ( Cronartium ribicola ). Some bears consume substantial amounts of dandelion and clover. However, these exotic foods provide little digested energy compared to higher-quality bear foods. Domestic livestock are of greater energetic value, but use of this food by bears often leads to conflicts with humans and subsequent increases in bear mortality. Lake trout, blister rust, and brucellosis diminish grizzly bears foods. Lake trout prey on native cutthroat trout ( Oncorhynchus clarkii ) in Yellowstone Lake; white pine blister rust has the potential to destroy native whitebark pine ( Pinus albicaulis ) stands; and management response to bovine brucellosis, a disease found in the Yellowstone bison (Bison bison) and elk ( Cervus elaphus ), could reduce populations of these 2 species. Exotic species will likely cause more harm than good for Yellowstone grizzly bears. Managers have few options to mitigate or contain the impacts of exotics on Yellowstone's grizzly bears. Moreover, their potential negative impacts have only begun to unfold. Exotic species may lead to the loss of substantial highquality grizzly bear foods, including much of the bison, trout, and pine seeds that Yellowstone grizzly bears currently depend upon.

Wyoming↗

USGS2001

Whitebark pine, grizzly bears, and red squirrels

Appropriately enough, much of this book is devoted to discussing management challenges and techniques. However, the impetus for action—the desire to save whitebark pine ( Pinus albicaulis ) - necessarily arises from the extent to which we cherish it for its beauty and its connections with other things that we value. Whitebark pine is at the hub of a fascinating web of relationships. It is the stuff of great stories (cf. Quammen 1994). One of the more interesting of these stories pertains to the dependence of certain grizzly bear ( Ursus arctos horribilis ) populations on its seeds, and the role that red squirrels ( Tamiasciurus hudsonicus ) play as an agent of transfer between tree and bear.

Book chapter↗

USGS1999

Fire, red squirrels, whitebark pine, and Yellowstone grizzly bears

Whitebark pine ( Pinus albicaulis ) habitats are important to Yellowstone grizzly bears ( Ursus arctos ) as refugia and sources of food. Ecological relationships between whitebark pine, red squirrels ( Tamiasciurus hudsonicus ), and grizzly bear use of pine seeds on Mt. Washburn in Yellowstone National Park, Wyoming, were examined during 1984-86. Following large-scale fires in 1988, we repeated the study in 1995-97 to examine the effects of fire on availability of whitebark pine seed in red squirrel middens and on bear use of middens. Half of the total length of the original line transects burned. We found no red squirrel middens in burned areas. Post-fire linear-abundance (no./km) of active squirrel middens that were pooled from burned and unburned areas decreased 27% compared to pre-fire abundance, but increased in unburned portions of some habitat types. Mean size of active middens decreased 54% post-fire. Use of pine seeds by bears (linear abundance of excavated middens) in pooled burned and unburned habitats decreased by 64%, likely due to the combined effects of reduced midden availability and smaller midden size. We discourage any further large-scale losses of seed producing trees from management-prescribed fires or timber harvesting until the effects of fire on ecological relationships in the whitebark pine zone are better understood.

Wyoming↗

USGS1990

Bear use of cutthroat trout spawning streams in Yellowstone National Park

Grizzly bears ( Ursus arctos ) and black bears ( U. americanus ) prey on spawning cutthroat trout ( Oncorhynchus clarki , formerly known as Salmo clarki ) in tributary streams of Yellowstone Lake. These tributary streams were surveyed from 1985 to 1987 to determine the presence and level of trout spawning activity and bear use. Indices were developed to enumerate spawner density and levels of bear use. Of 124 known tributaries of Yellowstone Lake, 48% had a spawning run. Of these spawning streams, 93% had associated bear activity, and 61% had associated evidence of bear fishing. Bears were apparently using more spawning streams and fish compared to 10 years earlier. Bear use of cutthroat trout spawning streams appeared to be largely a positive function of volumetric spawner density. We hypothesize that abundance and quality of stream-side vegetation relative to other foraging options influenced bear use. Intra- and interspecific avoidance among bears was suggested by patterns of spawning stream use. Less bear use of spawning streams than expected occurred within 1 km of park developments.

Idaho, Montana, Wyoming↗