• Diet and habitat of the little brown bat (Myotis lucifugus) in Interior and Northern Alaska

      Shively, Rachel; Barboza, Peregrine; Verbyla, David; Jung, Tom; Doak, Patricia (2016-05)
      Little brown bats are sensitive to cold winters but consistent records of roosts in interior Alaska for 30 years indicate that the range of this species expands into the subarctic. We hypothesized that the little brown bat in interior and northern Alaska has adapted to high environmental demands by shifting foraging strategies. We analyzed guano to describe prey composition by microhistology, DNA analysis, stable isotope analysis, and image fragment recognition software. Alaskan bats consumed moths and flies, which was similar to the diet of southern conspecifics. However, bats in Alaska also consumed spiders. The stable isotopes of N and C in hair from bats in interior Alaskan bats were significantly different from bats in Yukon and coastal Alaska, which indicated the use of a separate habitat through summer. We used citizen science to collect reports of bats that ranged over most of Alaska and included sightings in the Arctic during autumn. Alaskan bats stored similar amounts of body fat to southern bats in autumn but unlike southern bats that migrate over 200 km, radio tracked bats in Alaska migrated short distances (<100km) to hibernacula in human structures. Expansion of the range of the little brown bat is apparently associated with a shift in foraging behavior to include gleaning of arthropods from surfaces. Overwintering at the extremely low air temperatures in interior Alaska is unlikely. Consequently, the persistence of bats in interior and northern Alaska may be related to consistent availability of human structures.
    • Diet, breeding success, detectability, and density of the great horned owl (Bubo virginianus) at its northern range limit

      McConnell, Madison H.; Kielland, Knut; Breed, Greg; Shook, John (2019-05)
      I studied the diet, breeding success, detectability, and density of great horned owls (Bubo virginianus) in the Middle Fork of the Koyukuk Valley in Arctic Alaska. The study extended from the southern slopes of the Brooks Range to latitudinal tree line, the northern breeding limit of the species, and included what are likely to be the northernmost great horned owl nests on record (up to 68.0113 degrees north). I completed the study during the 2017 and 2018 breeding seasons, during years of high snowshoe hare (Lepus americanus) abundance. The focus of this study was to gain an understanding of how high snowshoe hare abundance influences the recruitment, diet, and distribution of this apex generalist predator, and to determine best methods of detecting great horned owls for similar studies in the future. I used motion sensor cameras on nests as well as pellet analysis for diet and breeding studies, and call surveys for information on detectability and density. Great horned owl diet consisted mostly of snowshoe hares by mass (mean 80%, range 65-99%), with an average prey size of 714 g (95% CI ± 34.26). Nestlings received an average of 459 g (95% CI ± 75) of prey per chick per day, and the proportion of hares in their diet positively correlated with fledging success (P = 0.01). During call surveys, length of playback was the most important factor in detecting great horned owls throughout 12 minute surveys, reaching 23% (95% CI = ± 6.4) at 3 minutes, and up to 80% (95% CI = ± 6.1) at 9 minutes. Inclusion of silent listening periods may lessen the chance of detecting great horned owls during playback surveys, though a larger sample size is needed (P = 0.18). There was no correlation between cloud cover and probability of detection (P = 0.60) or wind speed and probability of detection (P = 0.28). However, there was a positive correlation between temperature and probability of detection (P = 0.02). Call surveys gave an estimate of 4.1 great horned owls per square kilometer (z = 4.302, 95% CI = ± 2.63). This was the northernmost study of North America's most widespread year-round bird of prey, and the first density estimate at their northern breeding limit.
    • Direct and indirect effects of wolves on interior Alaska's mesopredator community

      Sivy, Kelly J.; Prugh, Laura; Lindberg, Mark; Kielland, Knut; Arthur, Steven (2015-12)
      Large carnivores may indirectly benefit small predators by suppressing competitively dominant mesopredators. However, our current understanding of interactions within the carnivore guild does not account for carrion subsidies provided by large carnivores, which could facilitate mesopredators during times of prey scarcity. This could be particularly relevant in northern ecosystems characterized by long harsh winters and decadal prey cycling. In Alaska, state-sponsored wolf (Canis lupus) control programs reduce wolf populations by as much as 50-80% across 8 game management units that collectively total over 165,000 km2, yet the impact of this practice on the Alaska's diverse mesopredator community remains unknown. We used a quasi-experiment resulting from a wolf control program in the upper Susitna River Basin that was adjacent to Denali National Park and Preserve lands, where wolves occur at naturally regulated densities. From January-March 2013 and 2014, we collected coyote (Canis latrans) and red fox (Vulpes vulpes) scats and conducted snow track surveys for wolves, mesocarnivores, and their prey. I quantified the relative strengths of direct and indirect effects of wolves on 5 mesopredator species while accounting for snowpack characteristics and small mammal abundance, and assessed winter diet overlap and composition by coyotes and red foxes in response to wolves and small prey availability. My findings indicated that wolves could strongly influence mesocarnivore communities in the Denali and Susitna systems, however despite a strong effect of wolves on coyotes, there was no evidence to support a mesopredator release cascade mediated by coyotes. Rather, I observed a near guild-wide response to wolf presence, whereby mesopredators were positively associated with wolves within each study area. The relative strength of top down versus bottom up effects in this study system further indicated that during a period characterized by low small mammal abundance, wolves were the strongest predictor of canid and wolverine occurrence. Coyote and red fox diet further revealed that carrion was a heavily used resource during this time of low prey abundance, yet red foxes may minimize competition with coyotes for carrion by increasing their use of voles. Finally, I present a hypothesis that local scale facilitation by large carnivores could lead to landscape patterns of suppression by large carnivores, suggesting a key link between abundance patterns and the structure of carnivore communities at different spatial scales relevant to conservation and management.
    • Dissolved organic matter in wetland soils and streams of Southeast Alaska: Source, Concentration, and Chemical Quality

      Fellman, Jason B.; Hood, Eran; Boone, Rich; Jones, Jeremy; White, Dan; D'Amore, David (2008-12)
      Dissolved organic matter (DOM) transported from terrestrial to aquatic ecosystems is an important source of C, N and energy for the metabolism of aquatic heterotrophic bacteria. I examined the concentration and chemical quality of DOM exported from coastal temperate watersheds in southeast Alaska to determine if wetland soils are an important source of biodegradable dissolved organic carbon (BDOC) to aquatic ecosystems. I addressed this question through a combination of high resolution temporal and spatial field measurements in three watersheds near Juneau, Alaska by using a replicated experimental design that characterized DOM export from three different soil types (bog, forested wetland and upland forest) within each of the watersheds. PARAFAC modeling of fluorescence excitation-emission spectroscopy and BDOC incubations were used to evaluate the chemical quality and lability of DOM. Overall, my findings show that wetland soils contribute substantial biodegradable DOM to streams and the response in BDOC delivery to streams changes seasonally, with soil type, and during episodic events such as stormflows. In particular, the chemical quality of DOM in streamwater and soil solution was similar during the spring runoff and fall wet season, as demonstrated by the similar contribution of protein-like fluorescence in soil solution and in streams. These findings indicate a tight coupling between wetland DOM source pools and streams is responsible for the export of BDOC from terrestrial ecosystems. Thus, seasonal changes in soil-stream linkages can have a major influence on watershed biogeochemistry with important implications for stream metabolism and the delivery of labile DOM to coastal ecosystems. Soil DOM additions in small streams draining the three soil types showed that DOM leached from watershed soils is readily used as a substrate by stream heterotrophs and at the same time modified in composition by the selective degradation of the proteinaceous fraction of DOM. These findings indicate terrestrial DOM inputs to streams are an important source of C to support stream heterotrophic production. Thus, the production of protein-rich, labile DOM and subsequent loss in stream runoff has the potential to be an important loss of C and N from coastal temperate watersheds.
    • Distribution and biogeography of the Alaskan hare (Lepus othus)

      Cason, Michelle M.; Olson, Link; Booms, Travis; Hundertmark, Kris; Sikes, Derek (2016-05)
      The Alaskan Hare (Lepus othus Merriam 1900) is the largest lagomorph in North America but remains one of the most poorly studied terrestrial mammals on the continent. Its current distribution is restricted to western Alaska south of the Brooks Range, but historical anecdotal accounts of occurrences north of the Brooks Range (the North Slope) have led to confusion over its past, present, and predicted distribution. To clarify the historical range of L. othus, we surveyed North American museum collections and georeferenced voucher specimens (Supplemental File Appendix 1.1). We also located a specimen from the North Slope of Alaska long presumed lost and whose identity had come to be questioned. The rediscovery of this missing specimen suggests the occurrence of at least one Alaskan Hare on the North Slope as recently as the late 1800s. Because unforested ecosystems such as tundra and Arctic grasslands have decreased in Alaska since the last glacial maximum, and L. othus occurs in unforested habitat, we expected to observe low genetic diversity in the mitochondrial control region of L. othus. However, with recently collected specimens from regions in Alaska that were poorly represented in the past (i.e. Alaska Peninsula, Little Diomede, and Kotzebue Sound), we discovered more genetic diversity and population structure than was found in previous studies, including similar haplotypes from the Alaska Peninsula and from eastern Russia. This suggests there may have been 2 distinct colonization events of northern hares in Alaska, or introgression from L. timidus and a mitochondrial sweep that has been restricted to the Alaska Peninsula and Bristol Bay area. Our morphological analyses of the difference between the two subspecies, L. o. othus and L. o. poadromus, were ambiguous, with principal components analysis and simple linear regression indicating the presence of a latitudinal size cline and discriminant function analysis revealing successful group assignment that is not solely based on latitude. Our research clarifies the current and recent distribution of the Alaskan Hare and reveals more genetic diversity than previously suspected in the mitochondrial control region. We also observed a new biogeographic pattern and closer mtDNA association with L. timidus, which, combined with new island specimens and observations, suggests gene flow across the Bering Strait. It also highlights the importance of maximizing sample sizes and sampling widely across a taxon’s geographic distribution.
    • Distribution and density of the American Red Squirrel (Tamiasciurus hudsonicus ) in the interior Alaskan old-growth forest for 2019

      Huettmann, Falk; Steiner, Moriz (2019-07-31)
      The aim of this project -carried out in July 2019 - was to determine the distribution and density of the American Red Squirrel (Tamiasciurus hudsonicus; taxonomic serial number 180166) in the old-growth forest of interior Alaska; region of Fairbanks. Also the distribution and density of squirrel middens (construction built by the squirrel, which is used for nutrition storing for the winter. Middens also provide as a nest for the squirrel's which can be used as protection from predators. We carried out opportunistic surveys along trails and within forest stands using GPS and notebook. Google Maps were used for navigation and planning help. This work can be used for subsequent model predictions with GIS software and other modelling software programs to obtain the detection rates and the distribution and density of middens in the whole study area (Tanana State Forest).
    • The distribution and phylogeography of the Alaska marmot (Marmota broweri)

      Gunderson, Aren M. (2007-12)
      The taxonomic and distributional status of the Marmota broweri has been the subject of much debate and confusion since it was first described as a subspecies of the hoary marmot (M caligata). Through a review of all museum specimens, published accounts of this species, field surveys, and the identification of previously unidentified marmot specimens we have determined the current distribution of the Alaska marmot to include the Brooks Range, the Ray Mountains, and the Kokrines Hills of northern Alaska. The Yukon River forms the boundary between the peripatric distributions of M broweri and M caligata in Alaska. Since M broweri was a resident of Beringia during the Pleistocene, I expect the phylogeographic structure of Alaska marmots (M broweri) to exhibit the signature of persistence in Beringia and subsequent expansion into glaciated areas. My objective is to investigate the phylogeographic structure of Alaska marmot populations through phylogenetic tree construction, measures of genetic diversity, a mismatch distribution, and nested clade analysis of DNA sequence data from the mitochondrial cytochrome b gene. I found significant geographic structure across the range of M broweri. The results of my analyses suggest a recent population expansion from central Alaska (Beringia) into the formerly glaciated Brooks Range
    • Distribution of hexachlorobenzene concentrations in spruce needle samples across Alaska

      Billings, Shane (2000-05)
      The global distribution of persistent organic pollutants has initiated considerable effort towards understanding long range atmospheric transport and partitioning of these potentially damaging compounds. Apparent latitude dependent concentration gradients of organic pollutants in otherwise pristine environments has given rise to a global fractionation model, coined the cold finger effect. According to the cold finger theory, semi-volatile persistent organic pollutant will show a preference for partitioning from the atmosphere to the ground and vegetation at northern latitudes. Here we present a study of hexachlorobenzene in spruce needle samples across Alaska, which offers a large range of climates, from its southern coastal rain forests to the northern arctic. The large variation in climate across Alaska should result in a measurable latitude dependent concentration gradient for HCB, if the cold finger effect is being realized. Spruce needle samples were extracted, cleaned, and analyzed by GC/MS. According to principle component regression analysis, HCB concentrations in all the spruce needle samples across Alaska show a strong positive correlation with lipid content of the needles. The HCB concentrations also show two distinct latitude trends. The spruce needle samples taken from the coast to approximately 63° north show relatively high HCB concentrations and a possible negative correlation with latitude. The samples between 63° and 68° north show a definite positive correlation between HCB concentration and latitude, which is consistent with the cold finger effect.
    • Distribution of hunter groups and environmental effects on moose harvest in Interior Alaska

      Hasbrouck, Tessa R.; Brinkman, Todd; Stout, Glenn; Kielland, Knut (2018-12)
      Moose (Alces alces) is one of the most valuable wild game resources in Interior Alaska. In recent years, residents of rural indigenous communities have expressed concern that climate change and competition from non-local hunters are challenging local moose harvest opportunities. I collaborated with wildlife agencies and village tribal councils to co-design two studies to address rural community hunter concerns. The first study assessed the spatial and temporal distribution of local and non-local hunter groups to examine areas of potential competition. The second study addressed changing environmental factors and their impacts on moose harvest. Although competition among local hunters or among non-local hunters certainly occurs, competition between local and non-local hunters, or between resident and non-resident hunters is a more common and reoccurring issue. Local hunters are those who hunt in the area in which they reside whereas non-local hunters travel away from the area they reside to hunt. I assessed hunting patterns by local and non-local hunters in a remote hunting region near the interior villages of Koyukuk and Nulato to quantify moose harvest overlap between these two user groups to assess potential competition. I used Alaska Department of Fish and Game (ADFG) moose harvest records to develop a relative competition index that identified locations and time periods within the hunting season where the greatest overlap occurred from 2000-2016. I determined that the highest competition occurred between 16-20 September (i.e., peak harvest period) and was concentrated predominantly along major rivers. To decrease overlap and mitigate potential competition between hunter groups we recommend providing information on competition hotspots to hunters, or lifting the no-fly regulation in the Koyukuk Controlled Use Area with the caveat that hunting with the use of aircraft must occur 1.6 km from the Koyukuk River corridor. These actions may provide hunters information on how to re-distribute themselves across the landscape and allow hunters to use areas away from rivers, where most harvest currently occurs. Additionally, climate change and seasonal variability have anecdotally been documented to impact moose hunting opportunities. Specifically, warm temperatures, delayed leaf drop, and fluctuating water levels are concerns expressed by some local hunters. I quantified changes in temperature, leaf drop, and water level near Koyukuk and Nulato and the subsequent relationships between these environmental variables and the total number of moose harvested using linear regression models. I used temperature data, gauging station data (i.e., water level), remote sensing data (i.e., leaf drop analysis), and ADFG moose harvest records and explored previously untested hypotheses and to quantify relationships from 2000-2016. I concluded that non-local hunter harvest success was more dependent than local harvest success on environmental conditions. Non-local harvest significantly increased with higher water levels from 6-10 Sept (p=0.02), 11-15 Sept (p=0.02), and 16-20 Sept (p<0.01), and decreased with warmer temperatures in the same three time periods (p<0.01, p=0.02, p<0.01, respectively). Local harvest increased with higher water levels from 16-20 Sept (p<0.01). These results quantitatively show that environmental factors do impact hunter success. I speculate that local hunter harvest success is less dependent on environmental variability because they have the ability to harvest opportunistically, rely more heavily on the resource, and reside near the hunting area. This ability to opportunistically hunt and adapt may give them an advantage over non-local hunters as environmental conditions shift with climate change.
    • Distribution of White Spruce in Alaska. An Open Access prediction surface from climatic and bioclimatic parameters using ESRI GRID formats.

      Huettmann, Falk (Bettina Ohse, Falk Huettmann, Steffi Ickert-Bond, 2008)
      This open access data set contains a spatially gridded distribution of White Spruce in Alaska (ESRI GRID format), predicted from climatic and bioclimatic parameters (temperature, precipitation, elevation, and aspect). A species distribution model, developed by Bettina Ohse, was used to determine the ecological niche of the species based on the environmental variables. The model was developed within TreeNet, a classification and regression tree software. The ecological niche was then projected into geographical space, resulting in a predictive map of the species distribution in Alaska (4km resolution, tested accuracy of c. 95 %). We used ArcGIS 9.2. Data sources were freely available for the global public, and so were all tools used (prediction algorithms and specific GIS tools). We promote these data and this concept as a role model how to model plant distributions in wilderness areas and for overcoming data gaps in species distributions world-wide. We encourage the use and update of these data for further updating of this concept and its findings.
    • Divergence, gene flow, and the speciation continuum in trans-Beringian birds

      McLaughlin, Jessica F.; Winker, Kevin; Takebayashi, Naoki; Hundertmark, Chris (2017-08)
      Understanding the processes of divergence and speciation, particularly in the presence of gene flow, is key to understanding the generation of biodiversity. I investigated divergence and gene flow in nine lineages of birds with a trans-Beringian distribution, including pairs of populations, subspecies, and species, using loci containing ultraconserved elements (UCEs). I found that although these lineages spanned conditions from panmixia to fully biologically isolated species, they were not smoothly distributed across this continuum, but formed two discontinuous groups: relatively shallow splits with gene flow between Asian and North American populations, no fixed SNPs, and lower divergence; and relatively deeply split lineages with multiple fixed SNPs, higher divergence, and relatively low rates of gene flow. All eight lineages in which two populations were distinguishable shared the same divergence model, one with gene flow without a prolonged period of isolation. This was despite the diversity of lineages included that might not have responded in the same ways to the glacial-interglacial cycles of connection and isolation in Beringia. Together, these results highlight the role of gene flow in influencing divergence in these Beringian lineages. Sample size is a critical aspect of study design in population genomics research, yet few empirical studies have examined the impacts of small sample sizes. Using split-migration models optimized with full datasets, I subsampled the datasets from Chapter 1 at sequentially smaller sample sizes from full datasets of 6 - 8 diploid individuals per population and then compared parameter estimates and their variances. Effective population size parameters (ν) tended to be underestimated at low sample sizes (fewer than 3 diploid individuals per population), migration (m) was fairly reliably estimated until under 2 individuals per population, and no trend of over- or underestimation was found in either time since divergence (T) or Θ (4Nrefμ) . Lineages that were split above the population level (subspecies and species pairs) tended to have lower variance at smaller sample sizes than population-level splits, with many parameters reliably estimated at levels as low as 3 diploid individuals per population, whereas shallower splits (i.e., populations) often required at least 5 individuals per population for reliable demographic inferences. Although divergence levels may be unknown at the outset of study design, my results provide a framework for planning appropriate sampling, and for interpreting results if smaller sample sizes must be used.
    • Diversification of the fern genus Cryptogramma across time and space

      Metzgar, Jordan S.; Ickert-Bond, Stefanie; Wolf, Diana; Windham, Michael; Takebayashi, Naoki; Pryer, Kathleen (2016-05)
      I examined diversification, biogeographic history and polyploidy within the parsley ferns (Cryptogramma) across multiple time scales. Cryptogramma is a small circumboreal genus of rock ferns in the large, diverse family Pteridaceae and is most closely related to the Asian genus Coniogramme and the monotypic Central American genus Llavea. I generated a combined six locus plastid sequence alignment (rbcL, rbcL-accD, rbcL-atpB, rps4-trnS, trnG-trnR, and trnPpetG) and a low-copy nuclear marker (gapCp) alignment for 40 accessions. Phylogenetic analysis of these datasets using maximum parsimony, maximum likelihood, and Bayesian inference demonstrate that all three genera are reciprocally monophyletic, with Cryptogramma and Coniogramme most closely related to one another. This analysis also recovered the monotypic Cryptogramma section Homopteris and sect. Cryptogramma as reciprocally monophyletic. Within sect. Cryptogramma, the unambiguously supported phylogeny supported recognizing most described species as reciprocally monophyletic clades that are mostly allopatric and can be delineated by a few morphological characters. The nuclear DNA phylogeny supported the hypothesis that the allotetraploid Cr. sitchensis originated from a hybridization event between the Asian Cr. raddeana and the Beringian Cr. acrostichoides, and the plastid DNA phylogeny revealed that Cr. acrostichoides was the maternal parent. In contrast, the tetraploid Cr. crispa appears to have originated as an autopolyploid from an undiscovered or extinct ancestor. Further phylogenetic investigation of European Cryptogramma species using DNA sequence data from 15 accessions from Europe and southwest Asia revealed that Pleistocene glacial cycles have created genetic partitioning of Cr. crispa into eastern and western clades and have also led to the formation of the Turkish auto-octoploid Cr. bithynica with Cr. crispa as the parental taxon. Divergence time estimates for key nodes were inferred using Bayesian analysis of the plastid data set coupled with secondary time constraints to reveal that crown group Cryptogramma began diversifying in the Oligocene, with most present-day species originating in the Pliocene and Pleistocene. The genus was inferred by likelihood-based ancestral area reconstruction of the chronogram and geographic distribution data to have originated in east Asia, with four colonization events reconstructed by vicariance or dispersal to the New World. My Bayesian Analysis of Macroevolutionary Mixtures (BAMM) showed no significant difference in speciation rates across time or among clades. The morphological stasis of Cryptogramma and its stable speciation rates in response to climate cycles during the Pleistocene suggest it will survive future range shifts caused by anthropogenically induced climate change.
    • Division of parental roles in the monogamous western sandpiper, Calidris mauri

      Neville, Juliette Aimee (2002-05)
      I investigated whether male and female Western Sandpipers (Calidris mauri) contributed equal amounts of parental care during the breeding season, near Nome, AK, USA (64 ̊N) during 1998 and 1999. I repeatedly observed which parent was present at the nest during incubation and which parent tended the brood during the brood care period. Females incubated predominantly at night (18:00-06:00 hr ADT); males incubated predominantly during the day (06:00-18:00 hr ADT). Males spent more time incubating than females (57% vs. 43%, P<0.05). Females deserted their broods on average 5.6 days after hatch, while males tended broods on average 13.0 days after hatch (P<0.001). Nests that hatched earlier in the season received significantly more bi-parental care during the brood care period (P=0.01). Timing of nest initiation had the greatest effect on the division of parental care between sexes for Western Sandpipers.
    • DNA recovery from latent blood after identification by fluorescein

      Martin, Laurie A. (2005-05)
      Luminol has been widely used in the field of crime scene investigations to detect latent blood; however, luminol has the tendency to destroy DNA evidence. Fluorescein, an alternative to luminol for detecting latent blood at a crime scene, had not been adequately evaluated for its impact on DNA evidence. This thesis demonstrates the successful recovery of DNA from a blood sample treated with fluorescein. DNA was extracted from blood-containing denim substrates after fluorescein was applied to the substrates. The DNA locus, D18S51, was amplified using standard polymerase chain reaction (PCR) techniques, separated by gel electrophoresis, and visualized using ultraviolet light. The results demonstrate that DNA was successfully recovered from the samples.
    • Do wintering conditions drive population trends in semipalmated sandpipers (Calidris pusilla)? Evidence from a corticosterone biomarker

      Boldenow, Megan L.; Powell, Abby; Kitaysky, Alexander; Lanctot, Richard (2018-05)
      Some of the most extreme long-distance migrants, Arctic-breeding shorebirds are disproportionately represented in tallies of declining species worldwide. For many shorebirds, including the semipalmated sandpiper (Calidris pusilla), the specific causes and mechanisms behind population declines have not been identified. Stressful conditions affecting birds during wintering are often implicated. Interactions between events and processes occurring in the disparate locations used throughout the annual cycle also may be critical in shaping both individual life histories and population demographics. The main objectives of my graduate research were: a) to examine whether semipalmated sandpipers wintering in specific locations incur differential levels of stress; and b) to test whether stressful conditions may carry over between different stages of an individual's life cycle. Using measurements of corticosterone (the primary avian stress hormone) deposited in winter-grown feathers, I examined the contribution of breeding season and fall migration to winter-incurred stress, and looked for evidence of carryover effects from wintering conditions to spring migration and subsequent reproductive performance. In Chapter 1, I compared the levels of stress exposure of 40 semipalmated sandpipers that bred at five Arctic sites and spent the austral summer in distinct regions (identified via light-sensing geolocators) across their tropical 'wintering' range. I found stress exposure varied by wintering region, and birds using locations along the Atlantic coast of northeastern South America and the Pacific coast of Central America had the highest feather corticosterone levels. I did not find evidence that carryover effects from the breeding season and/or fall migration influenced birds' physiology during winter. In Chapter 2, I investigated whether greater stress exposure during winter might subsequently affect birds during spring migration and/or breeding. I found that geolocator-tracked birds with increased stress levels delayed spring migration and initiated nests later. However, results for a larger dataset (including 254 birds breeding at seven sites across the North American Arctic) suggested low-stress birds nested later. It is possible the larger dataset included replacement clutches that could have confounded relationships with feather corticosterone, as only birds in better condition are likely to re-nest after clutch failure. In addition, I found evidence that stressful wintering conditions carryover to affect reproductive performance: females that accrued high levels of stress during wintering subsequently laid fewer eggs. In confirmed first nests, we found evidence for a clutch size-egg volume tradeoff, with high-stress females producing fewer offspring but potentially investing more in individual offspring. This research represents the first instance of the feather corticosterone technique being used to compare conditions across the wintering range of a calidrid shorebird and reveals specific wintering locations with high levels of stress exposure. This is also the first research that provides a mechanistic perspective on carryover effects between the wintering and breeding stages in a shorebird, through measurements of feather corticosterone. Finally, by showing that poor environmental conditions at wintering sites far from Arctic breeding areas may be detrimental to the reproductive performance of a species with declining populations, this research emphasizes the importance of considering full annual cycles in conservation and research efforts for migratory species.
    • Doppler sodar observations of the winds and structure in the lower atmosphere over Fairbanks, Alaska

      Kankanala, Pavan Kumar Reddy (2007-12)
      Fairbanks, Alaska (64°49ʹ N, 147°52ʹ W) experiences strong temperature inversions which when combined with the low wind speeds prevailing during the winter cause serious air pollution problems. The SODAR (Sound Detection And Ranging) or acoustic sounder is a very useful instrument for studying the lower atmosphere as it can continuously and reliably measure the vertical profiles of wind speed and direction,vertical motions, turbulence and the thermal structure in the lower part of the troposphere. A Doppler sodar was operated from December 2005 to April 2006 at the National Weather Service site in Fairbanks. The wind observations from the sodar indicate that the majority of the winds during the winter months were from the North, Northeast or the East, which is in good agreement with the radiosonde measurements and the long term trends in the wind patterns over Fairbanks area. Case studies were carried out using the sodar data depicting drainage winds, low-level jets, formation and breakup of inversions and estimation of the mixing layer height.
    • Double-difference relocation of earthquakes at Uturuncu Volcano, Bolivia, and Interior Alaska

      Hutchinson, Laura; West, Michael; Christensen, Douglas; Freymueller, Jeffrey (2015-08)
      In order to reliably interpret seismic patterns, we must have reliable earthquake locations. To improve our catalog locations, I incorporate cross-correlations into double-difference earthquake relocations to generate high precision relative locations. I perform relocations for two regions, one volcanic and one tectonic. At Uturuncu volcano, I incorporate a wealth of previous studies to present a picture of the processes at play. Seismic, gravity, InSAR, and electromagnetic studies all show that there is a magma body underlying the entire region, and chemical studies suggest that this magma body (the Altiplano-Puna Magma Body, or APMB) is the source of the large ignimbrite eruptions that have occurred in the past. The recent uplift has been modeled as a new batch of magma rising off the APMB, beginning the ascent as a diapir. My relocation results indicate that the seismicity aligns with the top of one of the imaged low velocities zones, which I interpret as a diaper beneath Uturuncu. The earthquakes mark the depth at which the crust is cool enough for brittle deformation. I also perform cross-correlations to determine families of similar events. These families are located around the summit of Uturuncu and display a radial pattern. This suggests that they are due to local volcanic stresses, such as inflation of the volcano, rather than regional stresses. In Interior Alaska, I study a region that is very seismically active, yet has no mapped Holocene faults. There are a series of seismic zones in the area, each comprised of NNE-striking seismic lineations. I perform earthquake relocations on 40 years worth of seismicity in order to refine and interpret fault planes. I additionally examine three earthquake sequences in the Minto Flats Seismic Zone (MFSZ). These earthquakes are large enough (≥M5) to produce an aftershock sequence to map out the rupture plane. I find that two of the three earthquakes occurred on WNW-striking planes, roughly perpendicular to the dominant direction of the seismic zone. The third earthquake ruptured along a NNE-striking plane but generated a WNWESE halo of aftershocks, suggesting that the basement is highly fractured in the region. The NW pattern that I find for the three sequences falls in line with my findings for the rest of the Interior: there are a series of NE-striking faults that are cut by NW-striking faults. Throughout the Interior, these faults cross at approximately 60°, suggesting that they are conjugate faults. I believe that the three earthquake sequences in the MFSZ are also conjugate faults and are a part of the broader conjugate system throughout the Interior.
    • Duckling survival and incubation behaviors in common goldeneyes in Interior Alaska

      Schmidt, Joshua Harold (2004-08)
      The lack of research on the common goldeneye (Bucephala clangula) in Interior Alaska prompted this study. My objectives were to estimate duckling survival relative to several explanatory variables and to characterize incubation behaviors in a subset of females nesting in the Chena River State Recreation Area. My estimates of duckling survival were higher than previously reported for this species: 0.65 (95% CI 0.49 to 0.82) and 0.68 (95% CI 0.58 to 0.79) for 2002 and 2003 respectively. Seasonally, duckling survival increased linearly throughout 2002, remained nearly constant in 2003, and was negatively related to daily precipitation in both years. Nest attendance patterns and incubation behaviors were not related to weather, female experience, clutch size, or day of incubation. Average number of recesses per day (2.9 ± 0.05), length of recesses (100.7 ± 1.5 min), and incubation constancy (79.8 ± 0.3%) were similar to values previously reported for this species (mean ± SE). I observed nocturnal recesses in this population. Although not previously reported for this species, these recesses may occur due to extended daylight hours during the incubation period.
    • Dynamics of the 240 A.D. caldera-forming eruption of Ksudach Volcano, Kamchatka, Russia

      Andrews, Benjamin James (2004-08)
      The Ksudach Volcano KS-1 rhyodacite deposits offer an opportunity to study eruption dynamics and plume stability during a caldera-forming eruption. Stratigraphic relations indicate four phases of eruption, Initial, Main, Lithic, and Gray. Well-sorted, reverse-graded pumice fall deposits overlying a silty ash compose the Initial phase layers. The Main, Lithic and Gray phases are represented by pumice fall layers interbedded with pyroclastic flow and surge deposits (proximally) and co-ignimbrite ashes (distally). Although most of the deposit is <30 wt.% lithics, the Lithic phase layers are>50wt.% lithics. White and gray pumices are compositionally indistinguishable, however vesicle textures and microlite populations indicate faster ascent by the white pumices prior to the Gray phase. The eruption volume is estimated as 7.5 km³ magma (dense rock equivalent) and 2.4 km³ lithics. Isopleth maps indicate mass discharge rates (MDR) ranged from 5-10x10⁷ kg/s in the Initial phase to> 10⁸ kg/s in the Main, Lithic, and Gray phases. Stratigraphic, granulometric, and component analyses indicate simultaneous eruption of buoyant plumes and non-buoyant flows during the Main, Lithic and Gray phases. Caldera collapse during the Lithic phase is reflected by a large increase in lithic particles and the textural change from white to gray pumices; collapse occurred after eruption of 2/3 of the magma.