Exponential rates of digestion are described for brown trout and whitefish for July, October, December (1969), and April (1970). The slope of the line fitted to the digestion data from each month was defined as the instantaneous rate of digestion and applied to an exponential growth model to determine the instantaneous consumption rate. The digestion and consumption rates were applied to field measurements of percent fullness to determine the amount of food material ingested during a 24 hour period. Brown trout consumed 127, 24, 19, and 84 mean percent of their stomach capacity in the July, October, December, and April studies. Whitefish consumed 74, 21, 46, and 51 mean percent of their stomach capacity in the same respective study periods. Mean daily ration from four major collection periods was calculated on fish in the 50 gram to BOO gram size range. Brown trout daily ration varied between 1.35 percent and 2.59 percent. Whitefish daily ration varied between 0.44 percent and 0.83 percent. Brown trout diets were quite variable with 44 percent of their caloric intake comprised of terrestrial invertebrates in October, 55 percent of the December calories comprised of fish eggs, and 39 percent of the April calories made up of Leptoceridae larvae. Emerging imagoes were important items in the brown trout diets, contributing as much as 62 percent and not less than 11 percent of the numeric intake for one collection period. Whitefish did not rely upon emerging imagoes as a significant food source. Their stomachs consistently contained mayflies, chironomids, and caddis larvae. Both fish species occasionally consumed substantial amounts of the large stonefly, Pteronarcys.

Currently, our ability to predict the flux of fine sediment at the watershed scale is limited by the precision of erosion rate estimates for the many potential sources distributed throughout a landscape as well as our understanding of the connectivity of sediment pathways during transport. In absence of a robust predictive model which can be validated by measurements of sediment fluxes and use of geochemical tracers. Predicting fine sediment yield at the watershed scale requires multiple redundant lines of information. This thesis outlines the methods used, and the data sets collected in the Root River watershed in Southeastern Minnesota, all of which are multiple lines of evidence to the sediment dynamics in the Root River. The research indicates that the Root River is a very dynamic watershed. The hydrologic regime of the watershed has shifted over the last half century. Due to this shift sediment fluxes are very dependent of the magnitude and sequence of events. Geomorphic analysis of the landforms and the use of a developed tool, TerEx, indicate that many reaches of the river have easily accessible near-channel sources of sediment. Sediment fingerprinting results illustrate that source tracer concentrations are variable across the landscape, that as a whole, upland sources are still a major contributor to the suspended sediment load, and that in some sub-watersheds near-channel sources are dominate in the suspended load. Over all the channel-floodplain exchange exerts strong control on the flux of sediment through this river system.

During the summer of 1976, five tame, trained mule deer (Odocoileus hemionus hemionus) were used to determine botanical composition and relative preference of mule deer diets on five habitat segments in the lodgepole pine (Pinus contorta) ecosystem of northeastern Utah. Diets were statistically analyzed according to estimated we1ghL consumption per unit of time spent feeding on the different segments. Habitat segments sampled were: clearcut forest, dry and wet meadow, mature forest, and stagnated forest. Diets differed between segments mainly because of differences in plant species available and their abundance. The diets in the non-forested segments averaged over 90 percent forbs,while in the forested segments forbs were only 65 percent of the diet. Differences are attributed to the low availability of forbs in the forested segments which are composed of over 90 percent browse, mainly grouse whortleberry (Vaccinium scoparium). Grasses and sedges were an insignificant part of the diet on all segments. Dietary differences based on forage classes were unimportant within the three non-forested segments as were diet differences within the two forested segments. Dietary differences based on estimated weight consumed per unit of time spent feeding were significantly different between all segments except the dry and wet meadow. The segments were thus ranked according to their importance as feeding areas for mule deer: 1. clearcut forest, 2. dry and wet meadow, 3. mature forest, and 4. stagnated forest. There was no apparent difference between diet composition computed from weight estimates and that computed based on bite counts for the first part of the summer. However, when mushrooms began growing and were eaten during the last part of the summer, comparisons of percent composition of diet derived from bite counts with that from estimated weights showed major differences. Especially was this true for diets from forested segments which had a larger proportion of mushrooms available in the community.

Anthropogenic perturbations to Arctic ecosystems have influenced large-scale climate processes, as well as finer-scale ecological relationships within and amongst populations of species. Life history theory predicts a trade-off between the temporal variation in a vital rate and its impact on population dynamics. Here, we examine the drivers of long-term variation in reproductive success in a sub-Arctic common eider (Somateria mollissima) colony, and evaluate the impacts of variation in reproductive success on eider population dynamics. In Chapter 2, we develop a suite of nest survival models to evaluate the effects of variation in predator abundance, the availability and spatial distribution of alternative prey, and breeding season climate on annual common eider nest success. Eider nest success declined across the 41 years of study, but was also highly variable across years. Annual variation in nest success was driven by a complex interaction between predators and alternative prey, as well as breeding season climate. Our results suggest that increased abundance of snow geese (alternative prey) may buffer annual fluctuations in arctic fox abundance, yet result in a long-term decline in eider nest success suggesting apparent competition via other predator species (e.g. gulls). The effect of breeding season climate was subtle compared to the influence of biotic factors and indicated that cold, wet conditions in early spring were correlated with decreased nest success, while warm, wet conditions in late spring increased eider nest success. In Chapter 3 we develop a stochastic population model to evaluate the relative effects of variation and covariation amongst multiple vital rates on population dynamics, and determine the impact of long-term changes in the abundance of alternative prey on eider population dynamics. Consistent with life history predictions, we found that proportional changes in adult survival have the largest impact on population dynamics, yet high variation in the vital rates underlying fertility contribute more to actual variation in population growth. The eventual exodus of alternative prey from the eider colony reduced the long-term growth rate, primarily through negative impacts on mean nest success.

Sewage, agricultural runoff, and atmospheric deposition have greatly increased the amount of nutrients (largely nitrogen (N) and phosphorus (P)) in surface water nationwide. Excess nutrients are associated with algal blooms and dissolved oxygen depletion in many water bodies, but linkages between nutrients and dissolved oxygen have been largely correlative. Biochemical oxygen demand (BOD) is a regulated water quality parameter that is aimed at describing the amount of oxygen consumed during the decomposition of organic matter. Despite the awareness that excess nutrients are linked to dissolved oxygen in rivers, few studies in the nutrient criteria literature discuss BOD measurements or how nutrients may impact BOD. Accordingly, I used factorial experiments to test the effect of inorganic nutrients (as N, P and N+P) and dissolved organic carbon on BOD measurements in Utah streams. The study was carried out from January through summer baseflow in 2011, allowing me to evaluate the effects of spatial and temporal variation of ambient nutrient concentration on oxygen demand. The study design included measurements in streams above and below nutrient point-sources (publicly owned treatment works) and several reference sites. I used classification and regression trees to identify thresholds of TN and TP that separate BOD response to nutrients into statistically distinct groups. My results show that seasonal variation affected BOD levels. As temperatures rose and water levels increased during peak runoff, I observed the highest BOD response to nutrient additions. I also found a significant correlation between BOD and ambient nutrient concentrations during that time period. I identified potential nutrient-related thresholds that could be used to assign numeric criteria that would protect designated uses. The threshold values I found for TN and TP were 0.56 mg/L and 0.09 mg/L, respectively. My results suggest that BOD may be sensitive to nutrient inputs and my experimental approach could be used as one line of evidence to support nutrient criteria related to aquatic life uses.

Eco-geomorphic interactions occur across a range of spatial and temporal scales from the level of the entire watershed to an individual geomorphic unit within a stream channel. Predicting the mechanisms, rates and timing of sediment production and storage in the landscape are fundamental problems in the watershed sciences. This is of particular concern given that excess sedimentation is considered a major pollutant to aquatic ecosystems. Rates of sediment delivery to stream networks are characteristically unsteady and non-uniform. Because of this, conventional approaches for predicting sediment yield provide incomplete and often inaccurate information. Terrestrial cosmogenic nuclides (TCNs) provide an estimate of spatially averaged rates of sediment yield from 101 to 104 km2 and temporally integrated from 103 to 105 years. Here, I used TCNs to constrain unsteadiness and non-uniformity of sediment yield within specific catchments of the Columbia River Basin (CRB). This is in combination with GIS analysis optically stimulated luminescence (OSL), Carbon-14 (C14) dating of fluvial deposits, and rapid geomorphic assessments. Results showed an order of magnitude spatial variability in the rates of millennial-scale sediment yield at the scale of the entire CRB. At the broadest scale long-term rates of sediment yield generally are poorly predicted from topographic and environmental parameters. A notable exception is the observed positive correlation between mean annual precipitation and sediment yield. Where functional relationships exist, the nature of those relationships are scale and situation-dependent. In addition to the broadest scale, each smaller watershed (e.g., ~ 10 – 2,000 km2) has a distinct geologic, geomorphic, and disturbance history that sets the template for the modern sediment dynamics and the physical aspects of aquatic habitat. Chapter 2 presents results of broad-scale trends while Chapter 3 is comprised of case studies from smaller watersheds. Finally, Chapter 4 explores the relationship between long-term sediment yield and modern channel form.

Pastures have been typically dominated by monocultures, only allowing herbivores access to one food type with unbalanced nutrient content and in some instances with single plant secondary compounds (SCs), which can be toxic if ingested at high concentrations. By establishing diverse pastures animals can select from a variety of plants with different concentrations and types of nutrients and SCs. The objectives of my study were to (a) determine if the type of plant diversity - tall fescue with either tannin-containing sainfoin or saponin-containing alfalfa − affects cattle preferences for these forages, (b) evaluate how readily fall-born calves reach finish body condition on these grass-legume pastures, and (c) determine the effects of sainfoin/tall fescue versus alfalfa/tall fescue pasture on meat quality and consumer acceptance. Foraging behavior, body weight, and pasture biomass before and after grazing was monitored when cattle strip-grazed 3 replications of 2 treatments repeated for 2 years (from May through September 2010 and from June through September 2012). Animals were allowed a choice between tall fescue and sainfoin [SAN] or alfalfa [ALF]) applied randomly in strips (fescue, legume, or fescue-legume mixture). No differences in average daily gains (~ 1 Kg/day) were detected between the 2 groups of cattle. I used scan samples at 5-min intervals from 0730 to 0930 to record foraging behavior. Animals spent most of the time grazing legumes and scans on legumes increased from the beginning to the end of the study. Scans and assessments of pasture biomass removal revealed greater use of sainfoin than alfalfa, whereas cattle in the ALF treatment removed more fescue than cattle in the SAN treatment. The presence of tannins in sainfoin likely contributed to these effects. Beef carcasses were very lean (select or standard quality grade), with 4-6% mean fat content. There were no differences between treatments regarding meat color, oxidative stability, fatty acid analyses, or consumer acceptance. Only 2 volatiles (nonanoic and decanoic acids) were greater in meat from the ALF treatment. Thus, cattle offered choices reached finish body weight at pasture and incorporated fescue into their diets even when legumes were available. The type of legume influenced foraging behavior but this effect did not impact animal performance, meat quality, or consumer acceptance.

The importance of surface water to chukar partridges (Alectoris graeca) and the feasibility of rain-catchment devices for improving chukar habitat were studied on the Thomas and Dugway Mountain Ranges in western Utah during 1969 and 1970. Sources of surface water were removed from one mountain rang~ and chukar populations on that range were compared with populations on an adjacent range with permanent sources of water. Providing drinking water did not improve chukar productivity, survival, or availability to hunters. Although most birds concentrated around water supplies in the summer, some chukars appeared to live completely independent of any permanent sources of surface water. Food habits of chukars near water did not differ from those in waterless areas. It was concluded that in habitats comparable to those studied, installation of rain-catchment devices is not a feasible technique for improving chukar habitat.

Since its inception, the National Wildlife Refuge System has been administered for management and restoration of habitat essential to the propagation and welfare of resident and wintering wildlife species. Acquisition of additional System units has been primarily directed to the benefit of the migratory bird resource. As of July 1, 1968 about 250 of the 321 refuge units were managed for the waterfowl resource (U. S. Department of Interior, 1968a). However, this growth of the System has been accompanied by an increase in recreational use of the refuges. In 1962, Public Law 87-714, the Refuge Recreation Act, was passed to provide direction for recreational development. The Act recognized that recreation must be limited in type and scope to avoid conflict with the primary wildlife management objectives. Although the primary function of the Refuge System is to meet the needs of wildlife, the entire System is based on the philosophical precept that the wildlife on these refuges is for the enjoyment of the public. It thus follows that refuges should provide for some public use. In recent analyses of America's resource picture, the fastest rising curves and projection are those of travel and the recreational use of wildlands (Clawson, 1963). Attendance records at our wildlife Refuges have grown at a rate of 12 percent annually. Except for boating and fishing at reservoir sites, the fastest growth in outdoor recreation since World War II has been in the use of National Wildlife Refuges (Clement, 1964).

Completely accurate statements of fishing pressure and harvest can only result from an ennumeration of all anglers and their catch. On most bodies of water it has not been economically feasible for management agencies to effect a complete census of fishermen and harvest. Practically, absolute accuracy is not necessary for management. The development of creel census methods resulting in estimates of known accuracy, yet requiring only a practical outlay of time and money, would be a step toward more effective management.