• Factors affecting body mass of prefledging emperor geese

      Lake, Bryce Cameron (2005-08)
      Body mass of pre fledging geese has important implications for fitness and population dynamics. To address whether interspecific competition for forage was broadly relevant to prefledging emperor geese, I investigated the factors affecting body mass at three locations across the Yukon-Kuskokwim Delta, Alaska. From 1990 - 2004, densities of cackling geese more than doubled and were 2-5x higher than densities of emperor geese, which were relatively constant over time. During 2003 - 2004, body mass of emperor geese increased with net above-ground primary productivity (NAPP) and grazing lawn extent and declined with interspecific densities of geese (combined density of emperor and cackling geese). Grazing by geese resulted in consumption of 90% of the NAPP that occurred during the brood rearing period, suggesting that interspecific competition was due to exploitation of common food resources. At six sampled locations, grazing lawn extent varied among- and within-locations, and was stable or declined slightly during 1999-2004, indicating reduced per capita availability. I conclude that negative effects of interspecific goose densities on body mass of pre fledging geese are partially responsible for recent declines in the fall age ratio of emperor geese because of a positive correlation between body mass and survival to fall staging areas. Management to increase the population size of emperor geese should consider interspecific densities of geese and interactions between interspecific densities and forage.
    • Factors affecting survival of Arctic-breeding dunlin (Calidris alpina arcticola) adults and chicks

      Hill, Brooke Lynne; Hunter, Christine M.; Lindberg, Mark S.; Lanctot, Richard B. (2012-05)
      Accurate estimates of, and identifying factors affecting, survival and productivity can provide insight into population trends and help determine what management actions would most benefit a population. Only limited demographic data are available for many Arctic-breeding shorebird species. I estimated survival probabilities for Arctic-breeding Dunlin (Calidris alpina arcticola); for adults between 2003 and 2010, and for chicks in 2008 and 2009. Adult apparent survival probabilities were higher for males (0.60 ± 0.04) than females (0.41 ± 0.05), were higher for individuals initiating nests earlier in the season, and yearly variation was high. These apparent survival rates appear insufficient to maintain a stable population. Daily survival rates of chicks increased as insect biomass increased across all ages and hatch dates, but the relationship with age and hatch date depended on the values of the other variables. The probability of a chick surviving to 15 days of age showed a strong relationship with hatch date, peaking in early July then declining rapidly. Chick survival was much higher for young from first nests (0.71 0.07) than early (0.23 ± 0.19) or late (0.03 ± 0.61) replacement nests. This suggests replacement nests make a much smaller contribution to annual recruitment than first nests.
    • Factors affecting the growth of a black guillemot colony in northern Alaska

      Divoky, George Joseph (1998)
      Annual variation in breeding populations at seabird colonies has been well documented, but there have been few long-term attempts to examine the environmental and demographic forces responsible. I studied breeding chronology and demography Black Guillemot in northern Alaska from 1975-1997 to identify the factors responsible for colony establishment and growth. The Black Guillemot is a cavity-nesting seabird whose populations are frequently limited by nest-site availability. Snowmelt in spring and snow accumulation in autumn had major effects on annual nesting initiation and success, respectively. Annual arrival at the colony and median date of egg laying was well correlated with the date of snow disappearance, with annual clutch initiation advancing 4.5 days per decade in response to regional climate amelioration. Successful breeding requires a snowfree cavity for ${>}80$ days. Decreased breeding success and post-fledging survival occurred in a year with a snow-free period ${<}80$ days. Historic weather records indicate annual snowfree periods ${>}80$ days were uncommon until the 1960's, when the species was first recorded breeding in northern Alaska. When additional nest sites were provided, growth of the colony was rapid, increasing from 18 pairs in 1975 to 225 pairs in 1989. Breeding numbers then decreased to 150 in 1996 as factors other than nest-site availability controlled population size.
    • Factors affecting the growth of a Black Guillemot colony in northern Alaska

      Divoky, George J. (1998-05)
      Annual variation in breeding populations at seabird colonies has been well documented, but there have been few long-term attempts to examine the environmental and demographic forces responsible. I studied breeding chronology and demography Black Guillemot in northern Alaska from 1975-1997 to identify the factors responsible for colony establishment and growth. The Black Guillemot is a cavity-nesting seabird whose populations are frequently limited by nest-site availability. Snowmelt in spring and snow accumulation in autumn had major effects on annual nesting initiation and success, respectively. Annual arrival at the colony and median date of egg laying was well correlated with the date of snow disappearance, with annual clutch initiation advancing 4.5 days per decade in response to regional climate amelioration. Successful breeding requires a snowfree cavity for >80 days. Decreased breeding success and post-fledging survival occurred in a year with a snow-free period <80 days. Historic weather records indicate annual snowfree periods >80 days were uncommon until the 1960's, when the species was first recorded breeding in northern Alaska. When additional nest sites were provided, growth of the colony was rapid, increasing from 18 pairs in 1975 to 225 pairs in 1989. Breeding numbers then decreased to 150 in 1996 as factors other than nest-site availability controlled population size. Annual population growth averaged 37% from 1976-1982 when nest site occupancy was low, 3% from 1983-1989 when all or most nesting cavities were occupied, and -6% from 1990-1996 as breeding productivity decreased and mortality of adults increased. Without immigration and with the average annual vital rates the colony would have had an annual rate of growth of 4% during this study. Contrary to published models of seabird colony growth, I found immigration important (>60% of annual recruitment) in all phases of growth. Philopatry showed previously unreported large variation among cohorts related to variation in nest-site vacancies at the natal colony and estimated recruitment opportunities at regional colonies. Philopatry was highest (>80%) for cohorts maturing when most regional recruitment opportunities were at the study colony but low (15%) when nest-site availability was likely similar at the natal colony and other colonies in the region.
    • Factors controlling the phenology and limits of hibernation in a sciurid

      Richter, Melanie M.; Buck, C. Loren; Barnes, Brian M.; Harris, Michael; Drew, Kelly; Kitaysky, Alexander (2015-08)
      Animals that live in seasonal environments have a variety of adaptations to survive periods of low to no food availability. One such adaptation is hibernation, which is characterized by profound decreases in activity, metabolic rate, and in most cases, body temperature. Among animals that hibernate, only two species are known to maintain low tissue temperature while defending significant temperature gradients, and the best studied of these is the Arctic ground squirrel (Urocitellus parryii). In the first chapter, we determine the lower ambient temperature limit of hibernation for an arctic ground squirrel (-26°C), and that a maximum torpid metabolic rate exists (0.37 mL O₂/g*h). This maximum torpid metabolic rate allows animals to defend a ~26°C temperature gradient between their core and their environment. In this chapter we also demonstrate that another, temperate, hibernating species, the golden-mantled ground squirrel (Callospermophilus lateralis), is capable of continuing hibernation at sub-freezing temperatures and can defend a temperature gradient of at least 9°C. Due to the extreme environment that Arctic ground squirrels inhabit, they have a very short growing season (~3-7 months) during which they must reproduce, grow, and accumulate energy stores prior to hibernation onset. In the second chapter we investigate the roles androgens play in hibernation phenology and male aggressive behavior. We use plasma samples collected from free-living animals and radioimmunoassays to determine circulating androgen levels. We then match the peaks in androgens to the timing of the two periods of male-male aggression (testosterone in the spring and dehydroepiandrosterone in the late summer/fall). We also present evidence to support testosterone as the main factor determining the timing of spring euthermy and emergence among reproductively mature males. In the third chapter we utilize captive animals to determine the importance of a cache to male reproductive development. Using three separate experiments, we show that while the accumulation of a cache in the late summer/fall may increase the likelihood of a male undergoing reproductive development, it alone may not be enough to ensure reproductive development. Additionally, we demonstrate that simply having access to ad libitum food in the spring is not enough to ensure reproductive development, nor is a restricted spring ration enough to prevent it.
    • Factors influencing the productivity of peregrine falcons (Falco peregrinus anatum) in the Fortymile wild and scenic river corridor, Alaska

      Jacobs, Jefferson M. (2003-05)
      I conducted the first comprehensive occupancy and productivity surveys of Falcon peregrinus on the Fortymile River during 2000 and 2001. I tested feather samples of nine nestlings for mercury contamination, examined effects of human disturbance, and assessed correlations of nest productivity to aspect and distance from ponds. Twenty and 22 nests were occupied in 2000 and 2001 and productivity averaged 0.88 and 1.33 nestlings per nest respectively. Mean feather mercury concentration was 3.85 ppm, and ranged from 1.88 ppm to 7.13 ppm. High variability in timing and intensity of disturbances and limited sample sizes precluded a study of disturbance effects. Peregrines selected nest-cliffs with southern aspects in 2001. North aspect nests were most vulnerable to failure in 2000. Nests within 6 km of a pond had higher productivity than those farther from ponds. The Bureau of Land Management is encouraged to continue annual occupancy and productivity surveys of the population.
    • Fault-hosted AU mineralization, Ester Dome, Alaska

      Cameron, Cheryl E. (2000-12)
      The Rhyolite gold prospect near Fairbanks, Alaska, appears to be different from most intrusion-related Au depositions within the Fairbanks area (e.g., Ryan Lode and Fort Knox), as it is located along a low-angle fault and is spatially associated with a quartz monozonite sill. A 1:60,000 scale geologic map was prepared using soil samples, airborne geophysical data, and mapping based on core and surface samples collected during 1998 and 1999. Mineralization does not appear to be temporally related to the quartz-monzodiorite sill, although mineralized fluids apparently used the sill as a pathway. ⁴⁰Ar/³⁹Ar dates of chloritized biotite from the intrusive (>75 Ma), sericite in mineralized gouge (9̃0 Ma), and white micas from metamorphic rocks (1̃00 Ma) correlate with dates from other plutonic-related deposits in the Fairbanks area ... Au-Ag, Au-Bi, and Au-As ratios suggest that the Rhyolite prospect is intrusion-related but distal to the causative body.
    • Feasibility Of Farm-To-School In Alaska: A State-Wide Investigation Of Perspectives From School Food Service Professionals

      Herron, Johanna Ruth; Bersamin, Andrea; Lopez, Ellen; Barry, Ronald; Henry, David (2013)
      Childhood obesity is a significant public health concern and schools are a key setting for prevention. The majority of U.S. children are enrolled in school where they consume a large portion of their daily energy. Farm-to-school programs are a promising strategy for preventing childhood obesity in school-aged children. The overall objective of this study was to conduct a baseline assessment of Alaska school food service professionals' perspectives of using local foods. Specific objectives were to: 1) Assess interest in utilizing local foods, 2) Identify perceived barriers to purchasing local foods, and 3) Determine resources needed to facilitate local food procurement. A survey was administered to all school food service professionals in Alaska (n = 74) who oversee the National School Lunch Program in their program site or district. The survey consisted of open and close-ended questions, comprising six domains: interest, perceived benefits, perceived usefulness, perceived barriers, and future needs. Descriptive statistics were performed on all variables. The majority (80-96%) of school food service professionals reported interest in utilizing local foods in the school meal programs. School food service professional's reported concern with finding a reliable supply (67%) and the cost (46%) of locally sourced foods. Nearly all (92%) school food service professional's agreed that information about what foods are available, where to purchase them, and USDA purchasing regulations would be useful. Farm-to-school strategies are attainable in Alaska. Interest is high, and perceived barriers and challenges are consistent with national findings. The most useful resources identified could be accommodated through increased communication and use of existing resources.
    • Feeding ecology of black oystercatcher (Haematopus bachmani) chicks

      Robinson, Brian H.; Powell, Abby; O'Brien, Diane; Konar, Brenda (2016-05)
      The Black Oystercatcher is an internationally recognized bird species of conservation concern and the focus of multiple monitoring programs due its small global population size, restricted range, vulnerability to human and natural threats in nearshore marine ecosystems, and the important role it plays as a top-level consumer in the intertidal food web. I studied a population of Black Oystercatchers in Kenai Fjords National Park, Alaska in 2013 and 2014, examining variation in chick diet, assessing methods used to monitor diet, and investigating the influence of provisioning on brood survival. To better understand the biases and limitations associated with the quantification of prey remains, I compared diet estimates from prey remains with two other methods: direct observation of adults feeding young, and diet reconstruction by stable isotope analysis. Estimates from collected prey remains over-represented the proportion of limpets in the diet, under-represented the proportion of mussels and barnacles, and failed to detect soft-bodied prey such as worms. I examined age- and habitat-specific variation in chick diet and found no relationship between diet and age of chicks; however, diet differed between gravel beach and rocky island nesting habitats. To determine the importance of diet on brood survival, I modeled daily survival rates of broods as a function of energy intake rate and other ecological factors and found that broods with higher intake rates had higher growth rates and daily survival rates. Given the consequences of reduced energy intake on survival, changes in the abundance and composition of intertidal macroinvertebrates as a result of climate change may have significant impacts on Black Oystercatcher populations. These findings highlight the importance of diet and provisioning to chicks and identify limitations of using prey remains to characterize Black Oystercatcher diet.
    • Feeding ecology of scaup ducklings across a heterogeneous boreal wetland landscape

      DuBour, Adam J.; Lindberg, Mark; Gurney, Kirsty; Hundertmark, Kris (2019-08)
      Understanding how patterns of food resources influence the behavior and fitness of free-living animals is critical in predicting how changes to such resources might influence populations. The boreal region of North America is relatively undeveloped and contains abundant freshwater lakes and wetlands. These largely pristine and stable habitats harbor high densities of aquatic invertebrates, which are a critical food source for the numerous waterbird species that breed in the boreal. Invertebrates are of particular importance for the optimal growth and survival of waterbird chicks. However, observations of long-term change to boreal aquatic habitats and their invertebrate populations associated with a warming climate has been implicated in the declines of some boreal breeding waterbirds, such as the lesser scaup (Aythya affinis). Lesser scaup are known to feed extensively on amphipods, a freshwater crustacean; however, ducklings have been shown to have a diverse diet. Our goal was to use the naturally occurring heterogeneity of aquatic invertebrates across boreal lakes within the Yukon Flats National Wildlife Refuge in interior Alaska to better understand how changes in invertebrate prey resources might affect diet selection and growth in lesser scaup ducklings. First, we used a stable isotope approach to quantify the variation in the trophic niche within our population of ducklings. We found that as a population, lesser scaup ducklings consume a variety of aquatic insects, crustaceans and mollusks, and that variation in the population diet is largely attributable to variation in diet between birds from different lakes with different invertebrate communities. Second, we used the same habitat heterogeneity to examine how gradients of invertebrate abundance relate to the growth of ducklings. We observed that lesser scaup ducklings experienced reduced growth rates in lakes that had little to no amphipods. Taken together, these results suggest that while lesser scaup ducklings are a flexible consumer that can adapt to changes in invertebrate populations, ducklings may face negative fitness repercussions when consuming prey other than amphipods.
    • Fire And Successional Trajectories In Boreal Forest: Implications For Response To A Changing Climate

      Johnstone, Jill Frances; F. Stuart Chapin, III (2003)
      Because of the key role played by fire in structuring boreal forest ecosystems, interactions between vegetation and fire regime may be an important and dynamic control of forest response to climate change. This research uses a series of field observations and experiments in boreal forests to examine the nature of several potential fire and vegetation interactions, and how such interactions may influence forest response to climate change. Long-term observations of post-fire succession provide information on the timing of tree establishment and the effects of early establishment on subsequent successional trajectories. The role of competitive interactions in driving patterns of early establishment was tested with experimental manipulations of aspen (Populus tremuloides) cover after fire. This research demonstrated that competition by aspen re-sprouts may reduce the success of conifer establishment and favor long-term dominance by deciduous trees. The effects of fire severity on successional trajectories were tested in a series of field experiments that contrasted patterns of seedling establishment across differences in depth of the post-fire organic layer. All species in the experiment responded negatively to decreased fire severity, but deciduous trees were more sensitive in their response than conifers. Thus, variations in burn severity are likely to mediate deciduous establishment in organic-rich stands. Observations of natural tree regeneration in stands that burned at different ages also indicate that a decrease in fire interval can influence the relative abundance of deciduous and coniferous species by reducing conifer establishment. Over longer time scales, changes in biota caused by species migration may influence fire and vegetation interactions. Observations of post-fire regeneration at the current distribution limits of lodgepole pine (Pinus contorta) indicate that continued range expansion of pine could initiate rapid shifts in dominance from spruce to pine within a single fire cycle. Together, these results provide insight into the dynamic feedbacks between fire and vegetation that can lead to high levels of system resilience, while also promoting rapid responses when threshold conditions are crossed. A more complete understanding of these interactions will improve our ability to manage and predict boreal ecosystem responses to a changing climate.
    • Fire severity effects on nutrient dynamics and microbial activities In a Siberian larch forest

      Ludwig, Sarah; Ruess, Roger; Kielland, Knut; Alexander, Heather (2016-08)
      High-latitude ecosystems store large amounts of carbon in soil organic matter and are among the most vulnerable to climate change. In particular, fire severity and frequency are increasing in boreal ecosystems, and these events are likely to have direct and indirect effects on climate feedbacks via increased emission of carbon (C) from soil and changes in vegetation composition, respectively. In this study we created experimental burns of three severities in the northeastern Siberian arctic, near Cherskiy, RU, and quantified dissolved C, nitrogen (N), and phosphorus (P), and microbial respiration and extracellular enzyme activities at 1-day, 8-days, and 1-year post-fire. Our objective was to determine how fire affects C, N, and P pools, soil microbial processes, and how these effects scale across severity and time since fire. We found labile C and nutrients increased immediately post-fire, but appeared similar to unburned controls within a week. Phosphorus alone remained elevated through 1-year post-fire. Leucine aminopeptidase activities initially increased with fire severity, but by 1-year, activities decreased with fire severity at a rate an order of magnitude faster. Fire severity suppressed phosphatase and β-glucosidase activities at all time points. Soil respiration was reduced by half in high severity plots 1-year post-fire, while net rates of N mineralization increased by an order of magnitude. We found that changes in soil C and nutrient pools, soil respiration, and net N mineralization rates responded in a threshold-fashion to fire severity, although P was uncoupled from C and N by changing at a distinct severity threshold. Extracellular enzyme activities and edaphic variables scaled linearly with fire severity. The interaction of threshold and linear response curves to fire severity may help explain the variability across studies in soil microbial community responses to fire. Microbial communities recovering from more severe fires have the possibility to decrease future ecosystem C losses through reduced respiration. The changing fire regime in permafrost ecosystems has the potential to alter soil microbial community dynamics, the retention of nutrients, and the stoichiometry of C, N, and P availability.
    • Fire-severity effects on plant-fungal interactions: implications for Alaskan treeline dynamics in a warming climate

      Hewitt, Rebecca E.; Hollingsworth, Teresa; Chapin, F. Stuart III; Rupp, T. Scott; Taylor, D. Lee (2014-08)
      Understanding the complex mechanisms controlling treeline advance or retreat in the Arctic and Subarctic has important implications for projecting ecosystem response to climate change. Changes in landcover due to a treeline biome shift could alter climate feedbacks and ecosystem services such as wildlife and berry habitat. Major sources of uncertainty in predicting treeline advance or retreat are the controls over seedling establishment at treeline and in tundra. One often-overlooked yet physiologically important factor to seedling establishment is the symbiosis with ectomycorrhizal fungi (EMF), the obligate mycobionts of all boreal tree species. EMF provide soil nutrients and water to seedlings and protect against pathogens, enhancing their growth and reducing drought stress. The availability of these critical mycobionts may be limited across the forest-tundra ecotone and by disturbance events such as wildfire. Wildfires are the primary large-scale disturbance in Alaskan boreal forests and are increasingly prevalent in tundra and at treeline. Fire is the major driver of boreal tree seedling recruitment; however, fire also alters the community structure and reduces biomass of EMF, especially after high-severity fires. To investigate the potentially critical role of EMF in seedling establishment at and beyond current treeline in Alaska, I conducted two observational studies and one experimental study that address how fire-severity influences EMF community structure and plant-fungal interactions. These studies indicated that shrubs that survived and resprouted after fires at treeline and in tundra were a source of resilience for EMF diversity and function. Shrubs maintained latesuccessional stage EMF taxa, and the EMF taxa associated with shrubs at treeline were compatible with tree seedlings that naturally established after fire. Many of the EMF taxa that were shared by seedlings and shrubs were present across the low Arctic, suggesting that EMF compatible with boreal tree species are not limited within the predicted geographic range of treeline expansion. Additionally, I found that seedling growth was correlated with post-fire fungal inoculum. Seedling growth was promoted by EMF inoculum provided by resprouting shrubs after fire. However, when fungal inoculum lacked EMF in post-fire tundra soils, seedling biomass was related to the negative effect of soil pathogens and the positive influence of dark septate endophytes. Together these results illustrate the important role of resprouting tundra shrubs as fungal nurse plants for establishment of boreal tree species at and potentially beyond current treeline, and that biotic factors such as EMF-tree interactions are important to seedling performance. My results suggest that the inclusion of biotic effects, like plant-fungal interactions, in simulation models of treeline dynamics will improve the accuracy of predictions of forestation and associated landscape flammability with future warming in Alaska.
    • Foliage and winter woody browse quality of an important Salix browse species: effects of presence of alder-derived nitrogen and winter browsing by Alaskan moose (Alces alces gigas)

      Burrows, Justin; Kielland, Knut; Wagner, Diane; Ruess, Roger (2019-12)
      In this study, I examined the relationship between soil nitrogen and winter browsing by moose on the physical and chemical characteristics of Salix alaxensis; specifically stem production, leaf nutritional quality, and stem nutritional quality of tissues produced the following growing season. I measured stem biomass production the 2013 growing season and offtake during the 2013-2014 winter browsing season at 16 sites on the Tanana River floodplain near Fairbanks, Alaska. I revisited the sites the following summer and autumn to assess regrowth and to collect soil, foliage, and stem samples. Browsing intensity and total soil nitrogen were similar in sites with and without alder, a nitrogen-fixing shrub. Soil nitrogen and browsing intensity were not consistently related to changes in stem or leaf quality, although there were significant relationships in some subsets. Soil nitrogen and browsing intensity also did not have consistent relationships with stem regrowth the following growing season. These results indicate that S. alaxensis growing in this system are able to recover from a naturally broad range of browsing utilization, including very high levels of offtake, and continue to produce nutritious leaves and stems.
    • Foods and foraging ecology of oldsquaws (Clangula hyemalis L.) on the arctic coastal plain of Alaska

      Taylor, Eric John (1986-09)
      The study was conducted from June to September during 1979 and 1980 in the the West Long Lake area of the National Petroleum Reserve-Alaska. Additional oldsquaws were collected in the inland wetlands near the northwest boundary of the reserve at Ice Cape. West Long Lake and the adjacent Goose Lake are located 15 miles south of the Beaufort Sea and immediately west of Teshekpuk Lake.
    • Foraging ecology and conservation biology of African elephants: Ecological and evolutionary perspectives on elephant-woody plant interactions in African landscapes

      Dudley, Joseph Paine; Bryant, John P. (1999)
      The available scientific evidence indicates that African forest elephants and bush elephants are ecologically and evolutionarily distinct taxa. The current practice of regarding these two taxa as ecotypes of a single species, Loxodonta africana (i.e., L. a. africana Blumenbach 1797, L. a. cyclotis Matschie 1900) appears unwarranted, and obscures issues of major significance to the conservation biology of African elephants. Under a proposed taxonomic revision, the African bush elephant retains the designation Loxodonta africana Blumenbach 1797 while the African forest elephant is recognized as Loxodonta cyclotis Noack 1906. The browsing of woody plants by African bush elephants is a major factor in the structural dynamics of semi-arid woodland and scrubland habitats in Hwange National Park (HNP) and the Sengwa Wildlife Research Area (SWRA), Zimbabwe. Drought, frost and fire also influence the structure and species composition of woody vegetation within HNP. Interactions among these three abiotic factors and elephant browsing may have significant impacts on the dynamics of semi-arid woodland and scrubland habitats of HNP. Mortality attributable to elephant damage was identified as a principal cause of death among large trees (>5.0 in height), and a relatively minor but not insignificant cause of death for shrubs and trees in the 1.0--5.0 in height class. The responses of Colophospermum mopane in SWRA to fertilization treatments corresponded to those predicted by the carbon/nutrient hypothesis of plant anti-herbivore defense. Comparisons of these results with those of previous studies suggest possible changes in the ecology and population biology of elephants in HNP during the past decade. Observed differences in the age-specific mortality of elephant in HNP during die-offs in 1993--1995 and 1980--1984 provide independent evidence of changes in the ecology of elephants in HNP during the period 1983--1993. The population of L. a. africana inhabiting the Matabeleland-Ngamiland-Okavango region of southern central Africa (which includes the HNP population), is the largest extant elephant population on Earth. The magnitude of this population (110,000--120,000), and the high proportion of its range currently under protection as wildlife reserves, indicate that this population may rank as the most viable and potentially sustainable elephant population on Earth.
    • Foraging Ecology And Sociality Of Muskoxen In Northwestern Alaska

      Ihl, Claudia; Ruess, Roger; Klein, David (2007)
      I investigated sociality and winter foraging ecology of muskoxen ( Ovibos moschatus) in Cape Krusenstern National Monument, northwestern Alaska. The nutritional value of moss (Hylocomium splendens, Tomenthypnum nitens) for muskoxen was evaluated by incubating moss in rumen-fistulated muskoxen and simulating post-ruminal digestion by incubation in acid-pepsin. Moss was indigestible in muskoxen and gained mass and nitrogen in the rumen. Consequently, high moss consumption during winter may result in net loss of nitrogen from a muskoxen's system. Local and regional differences in moss use by muskoxen and caribou or reindeer (Rangifer tarandus) were investigated in northwestern Alaska in relation to indicators of winter range quality. On muskox winter ranges, increases in fecal moss indicated decreased graminoid cover, harder snow, increased moss cover, and greater animal densities. Higher mobility of caribou than muskoxen during winter limits use of their feces to reflect local forage selection, but fecal moss may indicate caribou winter range quality on a larger, regional scale. Increasing proportions of moss in muskoxen feces may alert wildlife managers to shifts in forage availability due to changing snow conditions. Roles of male and female muskoxen in coordinating group movements were investigated during the snow-free season. Adult females led most activity initiations, foraging-bout movements, and spontaneous group movements. Rutting males actively manipulated female-led movements through herding and blocking. Leaders incurred no costs in terms of lost foraging time. Habitat use by muskoxen shifted from upland habitats in early summer towards lowland sedge meadows during rut. Muskox group sizes decreased from winter to summer to rut. Muskoxen foraging efficiency decreased with group size in spatially unlimited but not in spatially limited habitats. Adult males contributed least to group cohesion, and their presence may contribute to group fission during rut. A conceptual model is presented which discusses how habitat, foraging, social behavior, and predation threat contribute to group sizes, fission and fusion of muskox groups. Results from this study indicate that winter ranges used by muskoxen in Cape Krusenstern may be limiting, which suggests that numbers of muskoxen in this area will likely remain small. Therefore, hunting quotas should be low and limited to males only.
    • Foraging ecology of yellow-rumped warblers in an Alaskan boreal forest following a spruce beetle outbreak

      Bartecchi Rozell, Kristen (2004-12)
      I examined the foraging ecology of the Yellow-rumped Warbler (Dendroica coronata) several years after an outbreak of spruce beetles (Dendroctonus rufipennis) in the Copper River Basin, Alaska. With increased beetle-induced mortality of white spruce (Picea glauca), a preferred foraging substrate, we predicted warblers would respond through: (1) decreased overall use of white spruce, (2) increased selectivity of live white spruce that remained, and (3) reduced foraging efficiency, reflected by a greater proportion of time spent foraging and lower prey attack rates. We examined warbler foraging behavior and arthropod biomass on commonly used foraging substrates, and in stands with low-moderate (<40%) and heavy (>40%) spruce mortality. Live and dead white spruce, quaking aspen, and willow were the most commonly used foraging substrates, and selection of coniferous versus deciduous tree types varied by breeding stage. Yellow-rumped Warblers foraged extensively on dead spruce in stands with heavy spruce mortality, although they avoided it in stands with low-moderate spruce mortality. Dead spruce supported significantly lower arthropod biomass than any other tree type except black spruce, and warblers that foraged in dead spruce tended to have lower prey attack rates than when they foraged in live white spruce.
    • Forest Ecology And Distribution Of Bats In Alaska

      Parker, Doreen Ingrid; Cook, Joseph A.; Klein, David R.; Rexstad, Eric A. (1996)
      This thesis documents distribution of bat species in Alaska and effects of clearcutting on bat activity in temperate rainforests of southeastern Alaska. Occurrence of Myotis lucifugus, M. californicus, M. volans, M. keenii, and Lasionycteris noctivagans is confirmed in southeastern Alaska. I describe new specimens of M. keenii from southeastern Alaska, the first in over 100 years. Myotis lucifugus and Eptesicus fuscus are documented north of 64$\sp\circ$ N latitude. Environmental conditions and geography which influence distribution and latitudinal diversity gradients are discussed. Low bat activity in second-growth forests and clearcuts suggests that these areas provide little summer habitat. Higher activity levels in old-growth and riparian forests suggest these areas are important summer habitat. A change in activity between lactation and post-lactation periods is also noted. Unusual aspects of M. lucifugus ecology in southeastern Alaska are: consumption of spiders; presence of maternity colonies in a temperate rainforest; and intermittent use of hibernacula. <p>
    • Formation and optical properties of photochromic silver nanoparticles

      Lee, George Patrick (2005-05)
      Spherical silver nanoparticles may be produced by the reduction of Ag (aq) by borohydride in the presences of citrate. When (phenylphosphinidene) bis-(benzenesulfonic acid) is also present, and the reaction mixture is illuminated, nonspherical Ag nanoparticles are formed. We have discovered that the shape of some Ag nanoparticles can be repeatedly changed by subjecting them to numerous cycles of light and dark. To our knowledge, this has never been reported in the literature. These photo chromic Ag nanoparticles displayed at least two different particle shapes: prismatic and spherical. The difference in morphology could be determined by the color of the solution and by the electronic spectra. The prismatic Ag nanoparticles can be photochemically synthesized in 24hrs and then converted into a spherical form by placing them in the dark for 14hrs. This transformation is accompanied by a blue shift in the visible spectrum. The prismatic particles are reformed by placing them in the light for 4 hrs. This transformation has a red shift in the visible spectrum.