• Three Studies Of Impact Phenomena In The Solar System

      Chappelow, John E.; Sharpton, V. L. (2005)
      Meteoritic activity affects every body in the solar system; its effects are ubiquitous and therefore very useful in the exploration of many planetary bodies. This work addresses two different current problems associated with the use of impact phenomena in the study of other planetary bodies in our solar system. In Chapter 1 of this thesis, an original method of measuring depths and inferring cross-sectional shapes of impact craters using shadows cast within them by the Sun is developed. The method has the advantage of not requiring that the shadow-front pass through the center of the crater, as the current shadow-measuring technique does. It also has considerable advantages over the methods of stereogrammetry, which requires two images taken from different angles, and photoclinometry, which is sensitive to variations in reflectivity. Three examples providing a check of this method against real lunar impact craters, and demonstrating its utility, are provided. The rest of this work consists of two closely related studies of the effects of Mars's atmosphere, and its variations, on martian impact cratering and meteorite production rates. To date, little account has been taken of these, since the martian atmosphere has been considered too thin to have significant effects. Here, an original approach to the study of large impactor populations, and their effects on planetary surfaces, is developed and applied to Mars. The results show that for small crater sizes (2 m ? D ? 250 m) and impactor masses (10-1 kg ? m ? 107 kg), both processes depend strongly on atmospheric density. Even the current martian atmosphere is dense enough to produce meteorites of over 50 kg, and to substantially reduce small diameter (<30 m) impact cratering. Past, denser atmospheres would have had even greater effects. Therefore, Mars's atmosphere may interfere with surface age estimates based on counts of small craters, and its variations may be reflected in martian impact crater and meteorite populations.
    • Three-dimensional diving behavior of ringed seals

      Simpkins, Michael A.; Kelly, Brendan P. (2000)
      The three-dimensional movements of 13 freely diving ringed seals were recorded during the spring of 1990, 1991, 1992, 1996, and 1997 in the Canadian Arctic near Resolute Bay, Nunavut. These data were used to investigate the diving behavior of ringed seals more fully than was possible using previous data, which only recorded the vertical movements of diving animals (time-depth data). During a third of all dives, ringed seals focused much of their effort within a reduced volume, suggesting local search behavior within patches of prey. Local search occurred during descent, ascent, and bottom phases (time spent at depth between the end of descent and the beginning of ascent) of dives, but local search most commonly occurred during bottom phases. Location data from five seals were detailed enough to allow analysis of three-dimensional movements within individual dives. Behaviors were defined for the dives of these five seals based on the character of movements within the dives. Ringed seal dives included horizontally convoluted, travel, and exploration dives, but vertically convoluted, rest, and sit-and-wait foraging dives were not observed. Horizontally convoluted (presumed foraging), travel, and exploration dive behaviors were defined with similar frequency for V-shaped dives (dives with only descent and ascent phases) and U-shaped dives (dives with descent, bottom, and ascent phases). The lack of behavioral differences between dives with distinct time-depth profiles suggested that time-depth profiles were not a reliable means of classifying behavioral dive types for ringed seals.
    • Three-Dimensional Structure Of The Heliosphere: Quiet-Time And Disturbed Periods (Kinematic, Flare Propagation, Solar Wind, Interplanetary Magnetic Field)

      Fry, Craig Daniel (1985)
      An improved kinematic method is used to perform simulation studies of temporal and spatial variations of solar wind speed and interplanetary magnetic field during periods when the sun is quiet and when it is active. The procedure of Hakamada and Akasofu (1982) is improved and calibrated with a one-dimensional magnetohydrodynamic solution of solar wind flow. The solar-cycle evolution of solar wind velocity is studied using the data sets of King (1979, 1983) and Hoeksema et al. (1982, 1983) for the period 1976 to 1982. It is found that the gradient of the quiet-time solar wind speed as a function of magnetic latitude is steepest near solar minimum and most broad at solar maximum. The background solar wind velocity and magnetic field are simulated and compared to observations near the earth. Three-dimensional representations of the heliospheric current sheet (HCS) are displayed out to 5 AU for idealized dipole and quadrupole cases, and for observed source field configurations. The high latitude IMF and surfaces of constant magnetic latitude are also presented. The propagation of solar wind disturbances in the solar equatorial plane to 30 AU is simulated. Two major disturbance event periods are simulated, and it is seen how a series of solar flares can greatly disrupt both the inner and outer heliosphere. Visual representations of the distorted HCS due to a series of hypothetical solar flares are presented. A method of generating the polar component of the IMF vector, B(,z), is also developed. It is shown that field-line motion at the source surface provides a mechanism for the propagation of B(,z) into interplanetary space. This study shows that an improved kinematic method can be used to quantitatively model the three-dimensional heliospheric structure. Such a modelling scheme, which takes the stream-stream interaction into account, is necessary for the accurate prediction of near-earth solar wind parameters during quiet times and active periods.
    • The three-dimensional structure of the summit magma complex at Kilauea volcano, Hawaii, from travel time CDI tomography

      Pearson, Aaron David (2001-05)
      Methods of seismic tomography have been applied to Kilauea Volcano, Hawaii several times to determine the structure of the magma conduit system. The shallow summit chambers are the least defined part of the magma system. A dense seismic array ... was deployed over the summit in January, 1996 and February, 1997. P- and S- phase travel times of 271 earthquakes recorded at these stations were inverted with a new tomography algorithm developed by Clippard (1998) to highlight small, anomalous regions. A large (26.2 km³) low P-phase velocity anomaly (9% perturbation) was imaged beneath the summit caldera implying a body of approximately 9% partial melt. Several small anomalies of Vp/Vs = 2.7 beneath Kilauea caldera and the East Rift Zone are also interpreted as localized pockets of melt, gas and/or highly fractured material.
    • Threshold management strategies for exploited fish populations

      Zheng, Jie (1994-05)
      Under a threshold management strategy, harvesting occurs at a constant rate but ceases when a population drops below a threshold. The threshold approach seeks to enhance long-term yield of a population and to maintain population renewability. I evaluated threshold management strategies for selected herring and pollock stocks in Alaska. First, I examined stock-recruitment data from 19 major herring stocks worldwide to provide the basis for evaluating threshold management strategies. Seventy-three percent of these stocks exhibited statistically significant density-dependence. Most stocks have compensatory, dome-shaped stock-recruitment curves. Then, I simulated threshold management strategies for eastern Bering Sea (EBS) pollock and herring and Prince William Sound (PWS) herring using a single-species model. I further examined seven alternative threshold estimation methods. Cohort analysis, catch-at-age analysis, and catch and population sampling yielded estimates of population parameters. The objective function was a weighted function of increased average yield and decreased standard deviation of yield over a planning horizon. Compared to a non-threshold approach, threshold management strategies increase the long-term average yields, stabilize population abundances, shorten rebuilding times, and increase management flexibility. For a maximum yield criterion and Ricker stock-recruitment models, optimal fishing mortalities are slightly above fishing mortalities at maximum sustained yield (MSY), and optimal threshold levels range from 40% to 60% of pristine biomass for EBS pollock, from 40% to 50% for EBS herring and from 30% to 60% for PWS herring. With fishing mortality at MSY and the criterion of equal trade-off between yield and its variation, optimal thresholds range from 20% to 30% of pristine biomass for pollock. With the status quo exploitation rate of 20%, optimal thresholds range from 10% to 25% of pristine biomass for EBS herring, and from 5% to 25% for PWS herring. Of the threshold estimation methods evaluated, default percentage of pristine biomass usually performs best. Loss of yield due to errors in threshold estimation is small, generally under 10%. A bout 15 to 20 years of data are required to obtain a reliable estimate of thresholds. With single-species dynamics, the form of the stock-recruitment curve, exploitation rate and management objective are the most important factors affecting optimal thresholds.
    • Through the looking glass: constructing sexual identity

      Foore, Kimberly Ann (2004-05)
      The present research explored how contemporary women define their sexual identity and communicate their needs/wants for sexual gratification during the act of sexual intimacy. Using human science epistemology, methodology, and methods, eight women's narratives were co-constructed into two emergent themes: Defining sexuality as self-stereotyping identity and Setting the stage for uncertainty as mask. This research explored the unique definitions of sexuality from the co-researchers perspective and ultimately determined that sexual identity is inextricably bound to self-presentation and impression management. It was also discovered that these women communicate their sexual needs nonverbally and 'hide' behind a mask of uncertainty out of a culturally developed fear of being judged and/or labeled negatively for being too sexually experienced.
    • Thrust-breakthrough of folds southwest of Galbraith Lake, central Brooks Range, Alaska

      Grischkowsky, Elizabeth A. (2002-05)
      Detailed mapping of a 32 square-kilometer area in the fold-and-thrust belt of the north-central Brooks Range indicates that fault-related folds in the Lisburne Limestone formed as detachment folds and were subsequently cut by thrust faults. Thrust faulting resulted in a duplex structure with a floor thrust in the Kayak Shale and a roof thrust in the Siksikpuk Formation. The linking thrusts of the duplex dip toward the hinterland while the floor and roof thrusts dip toward the foreland indicating that the duplex has been tilted by underlying structures. I constructed models for the sub-lisburne structure to account for the structural geometry observed in the study area. Duplexing of the Kanayut Conglomerate is the most likely cause of the forward tilt, but thickening of the Kayak Shale or deformation beneath the basal thrust of the Endicott Mountains allochthon may also contribute.
    • Thule Plant And Driftwood Use At Cape Espenberg, Alaska

      Crawford, Laura J.; Potter, Ben; Alix, Claire (2012)
      This thesis addresses the question of Thule plant and woody fuel use at Cape Espenberg, Alaska between approximately AD 1500 and 1700. The objective of this thesis is to determine how the Thule at Cape Espenberg were using various plant species, including edible plant species and fuelwood species. Few studies have been done on prehistoric Arctic plant use, and so this study intends to add to this nascent but growing field. By examining charcoal and macrofossil remains, this thesis is also intended to discover similarities and differences between the Thule and their modern Inupiat descendants in terms of plant and woody fuel use. Statistical tests and descriptive analyses indicate that plant foods contributed significant nutrition to the Thule diet at Cape Espenberg, that woody fuel was used heavily, and also actively conserved with the incorporation of alternative fuel sources such as bone and blubber. This exploratory study underscores the importance of plants in prehistoric Arctic economies, and the need for future research.
    • Thyroid hormone binding to brain nuclear extracts during smoltification in coho salmon

      Cheek, L. Michael (1991)
      Salmon complete a metamorphosis called smoltification prior to entering salt water. Increased thyroid activity, olfactory imprinting, and chemical and structural changes in the brain are known to occur at this time. This study was undertaken to determine if triiodothyronine (T$\sb3$) binding to brain nuclear extracts changes during smoltification. During this investigation serum thyroxine (T$\sb4$) concentrations increased three fold during smoltification coincident with changes in coloration and morphology and surged again during downstream migration to six times presmolt concentrations. Using ultrafiltration assays, homologous displacement experiments of KCl extracts of recovered brain cell nuclei indicated that maximal binding capacity increased during smoltification and down-stream migration. The increase in receptor concentration lagged the increase in serum thyroxine by one week. Dissociation constants increased during smolt transformation but declined abruptly during down-stream migration. However, dissociation constants did not change during smoltification if nuclear extracts had been previously incubated at room temperature to remove endogenous ligand. Dissociation rate increased significantly, coincident with the increase in receptor concentration measured by homologous displacement. The maximal probable percent occupancy of available receptors increased from 60% before to greater than 95% during the smolt transformation climax. These results provide evidence that thyroid hormone receptors participate in brain development and olfactory imprinting in smolting salmon.
    • Till deformation beneath Black Rapids Glacier, Alaska, and its implication on glacier motion

      Truffer, Martin; Harrison, W. D. (1999)
      The motion of a glacier is largely determined by the nature of its bed. The basal morphology and its reaction to the overlying ice mass have been subject to much speculation, because the glacier bed is usually difficult to access, and good field data are sparse. In spring 1997 a commercial wireline drill rig was set up on Black Rapids Glacier, Alaska, to extract cores of basal ice, subglacial till, and underlying bedrock. One of the boreholes was equipped with three tiltmeters to monitor till deformation, and a piezometer to record pore water pressure. The surface velocity and ice deformation in a borehole were also measured. The drill successfully reached bedrock twice after penetrating a till layer, some 5 to 7 m in thickness, confirming an earlier seismic interpretation. The till consisted of a sandy matrix containing clasts up to boulder size. Bedrock and till lithology indicated that all the drill holes were located to the north of the Denali Fault, a major tectonic boundary along which the glacier flows. The mean annual surface velocity of the glacier was 60 ma-1 , of which 20 to 30 ma-1 were ice deformation, leaving 30 to 40 ma-1 of basal motion. The majority of this basal motion occurred at a depth of more than 2 m in the till, contradicting previously held ideas about till deformation. Basal motion could occur as sliding of till over the underlying bedrock, or on a series of shear layers within the till. This finding has implications for the interpretation of the geologic record of former ice sheets, for geomorphology, and for glacier dynamics. The effect of a thick till layer on ice flow and on quantities observable at the glacier surface was calculated. These include velocity changes on secular, seasonal, and shorter time scales. A mechanism for uplift events and dye tracing responses was suggested. An easy surface observation that could serve to clearly distinguish a glacier underlain by till from the more traditional view of a glacier underlain by bedrock could not be identified.
    • Time and space scales of some oceanic and atmospheric parameters in the Gulf of Alaska

      Beegle, Cynthia Juyne (1986-05)
      Time series of monthly means up to 65 years long were examined to determine the time and spatial scales of variablity in the Gulf of Alaska. Sea level, sea level pressure (SLP), air temperature, fresh water discharge, sea surface temperature (SST) and the Southern Oscillation Index (SOI) are the variables chosen to gain insight into local and global responses in the gulf. This study reports four major results. 1) Sea level anomalies (variations from the annual cycle) are driven by wind and fresh water; temperature effects in sea level are not seen. 2) SST anomalies cannot be predicted from sea level data, but SLP in southeastern Alaska and air temperature in Seward may be useful indicators on a two to three month time scale. 3) On the whole, anomalies in coastal and interior Alaska weather occur together, with SLP 180° out of phase with air temperature and precipitation. Using empirical orthogonal functions, the Southeast and Southcoast district can be separated. 4) A statistically significant SOI signal is seen is both SLP (p>0.995, Seward) and sea level (p>0.995) records.
    • Time synchronization and system support for energy efficient wireless sensor networks

      Lewis, Oldrine George (2007-08)
      This thesis presents a design of a Wireless Sensor Network (WSN) and the implementation of an original time synchronization algorithm. The complete system support for energy efficient WSNs was developed. The new time synchronization algorithm called Sliding Clock Synchronization employs a simple, yet very effective algorithm to compensate for static and dynamic drifts in the frequencies of crystal oscillators used in the WSN nodes. As power is a very scarce and critical resource in most WSN s, a tight synchronization algorithm can reduce power consumption thereby increasing the life of a WSN. An accurate and reliable synchronization algorithm also enables the WSN to be used for applications that require a tight synchronization for data correlation. A hardware and software interface for an embedded web server has been provided so that the WSN can be monitored and controlled over the Internet. An interface for a GPS module enables the network to incorporate GPS time stamps in recording network events. A sensor node emulator has been developed so that a single node can emulate multiple nodes without additional hardware, thus providing a simple and cost, effective means to test the network performance with large number of nodes.
    • Time-dependent electron transport and optical emissions in the aurora

      Peticolas, Laura Marie; Lummerzheim, Dirk (2000)
      This thesis presents the first time-dependent transport model of auroral electrons. The evolution of the spherical electron intensity in phase space is studied for a variety of incident electron intensities. It is shown that the secondary electrons with energies <10 eV and at altitudes >150 km can take over 300 ms to reach steady state in phase space. Since there are bright optical emissions in this region, such a time dependence in the auroral electrons is important. The emissions of N2(2PG) 3371 A and <math> <f> <rm>N<sup>+</sup><inf>2</inf></rm></f> </math> (1NG) 4278 A are studied for time-varying electron pulses to show for the first time that this ratio will change until the secondary electrons reach steady state in the ionosphere. The way in which the 3371A/4278A ratio changes with time-varying precipitation depends on the precipitating electron spectra. The changes in the emission ratio can be used to learn more about the auroral acceleration region and the role of the ionosphere in auroral emissions. Field-aligned bursts (FABs), often observed in electron spectra of instruments flying over flickering aurora, are modeled with the time-dependent transport model. How the ionosphere modifies these electrons is shown. The 3371 and 4278 A emissions of flickering FABs are modeled to study the optical effects of modulated electron intensities in time. A study of 4278 A emissions for electron source regions from 630 to 4,000 km are studied along with frequency variations from 5 to 100 Hz. This study shows that the percent variation of the maximum to the minimum column brightness is less for higher frequencies and more distant source regions. It is shown that with an accurate time-dependent transport calculation and 4278 A emission observations of flickering aurora it should be possible to deduce the source altitude of the modulated electrons creating the optical flickering.
    • Timing of breeding and reproductive success in a subarctic population of yellow warblers (Dendroica petechia)

      Sowl, Kristine Marie (2003-12)
      Detailed knowledge of reproductive rates is necessary for understanding population dynamics, but this information is lacking for many populations of migratory songbirds. I examined breeding chronology and reproductive success of Yellow Warblers (Dendroica petechia) breeding in east central Alaska in 1997-2000. Yellow Warblers nested in both spruce forest and willow shrub habitats, but breeding density and nest success were greater in shrub habitat. Annual productivity was influenced by the number of breeding attempts per female, clutch size, success of individual eggs or nestlings, and nest success. Mean clutch size was larger than in lower latitude populations and decreased seasonally. The abbreviated breeding season limited opportunities for replacing lost clutches or broods, but enough females replaced failed nests to increase annual productivity by 0.5 fledglings per female, on average. Nest predation was likely the primary cause of nest failures and was greater on the edge between willow shrub and spruce forest than within the interior of those habitats. Timing of breeding was consistent in three years of the study, but early laying in 1998, which coincided with warmer air temperatures, effectively extended the breeding season. Extremely low nest success lowered annual productivity in 1998, despite the extended breeding season.
    • The Tingmiukpuk site (KIR-273): a prehistoric site along the Killik River, Alaska

      Robertson, Aaron C. (2002-05)
      Tingmiukpuk (KIR-273), a prehistoric archaeological site, lies in a dune field on the east bank of the Killik River in Gates of the Arctic National Park and Preserve. The site consists of several surface scatters of cultural material on and around three large dune prominences. Field research was conducted during the summers of 1990, 1991, 1993, and 1999. Diagnostic artifacts and dates on surface faunal material suggest the presence of two archaeological components: one belonging to the American Paleoarctic tradition, and one to the Arctic Small Tool tradition. Artifacts and faunal material suggest that the site was used for processing caribou (including breaking bones for marrow and grease extraction). A variety of lithic tools associated with the hunting and processing of caribou were recorded, but most were manufactured off-site. The manufacturing of expedient tools (scrapers and utilized flakes), blades, and microblades was the primary lithic production activity at the site.
    • Tiny robots in our pockets: a critical exploration of podcasts

      Dreasler, Quinn Elizabeth; Coffman, Chris; Stanley, Sarah; Harney, Eileen (2015-05)
      This project is an exploration of the audio platform of podcasting. It is in three parts. The first part is an initial introduction to the medium of podcasting and an introduction to a critical theory of media studies in regard to popular culture. The second part is an exploration of the educational and academic applications of podcasting as well as an examination of aural learning as an important cultural mode of discourse. There are pedagogical implications and examples of utilizing both popular culture and podcasting in the classroom. The third part is a critical examination of selected podcasts that feature discussions of popular culture and how those discussions fit into the critical modes, genres and discourses outlined in the first two parts of this project. This discussion focuses mostly on the critical examination of science fiction films in podcasting. There is a conclusion that wraps up the main ideas and critical theories discussed in the project as well as an epilogue that addresses concerns raised at the defense of this project regarding pedagogy and accessibility. This is the transcript of this project. The actual thesis artifact is a series of three podcasts that are available through the University of Alaska Fairbanks Graduate School Archive and through the website SoundCloud. (https://soundcloud.com/quinn-dreasler/sets/quinns-thesis)
    • Tire chain damage on bridge deck wearing surfaces

      Muench, Wilhelm; Hulsey, J. Leroy; Barnes, David L.; Perkins, Robert A. (2017-12)
      A light weight, durable, and damage-resistant material is needed as a wearing surface replacement for a two-lane bridge deck that is on a 6% grade. The wearing surface to be replaced is 9.2-m wide and is attached to an orthotropic closed cell steel deck that supported by two 155.9-cm wide by 414.0-cm deep steel box girders. This is a 699.5-m long six span bridge over the Yukon River located near the Arctic Circle on the gravel road section of the Dalton Highway. The bridge is located approximately 80 km north of Fairbanks, Alaska. The structure was designed in the early 1970's with a 127-mm two-layer timber deck wearing surface. Since then, the timber deck wearing surface has been replaced in 1981, 1992, 1999, and 2007. Future decking material may be composites. Factors to be considered in the selection of a new decking material include: thermal cracking, abrasion, durability, flexural strain, traction, weight, and fastening methods to the steel deck. Moreover, the material must retain its structural properties in temperatures that range from -50C to 40C. For a majority of the year, the driving surface is covered with ice and snow. Because of the steep grade, trucks typically use tire chains during the winter. These tire chains damage the current timber wearing surface and are a major factor in its deterioration. Further, the more traffic the less traction. Owing to the damage tire chains cause on the current timber wearing surface, other wearing surface materials are being considered. The purpose of this project was to evaluate possible wearing surface in the laboratory for punching shear, structural strain, modulus, traction, and resistance to tire chains. In this paper, preliminary test results for traction, and wear by tire chains are presented. This is an updated version of a paper that was first presented at ISCORD 2007, Proceedings of the 8th International Symposium on Cold Region Development, Tampere, Finland, September 25-27, 2007, with co-author, J. Leroy Hulsey.
    • To freeze or not to freeze: that is the question: a look at freezeback landfills and final cover designs

      Durand, Sarah; Perkins, Robert; Aggarwal, Srijan; Barnes, David (2019-12)
      Freezeback landfills are an exciting concept but challenging in execution. There is not a single variable that leads to the success of a freezeback landfills but multiple variables in balance with each other that allow for freezeback to occur. Freezeback landfills should be engineered to the site-specific environment at the initial design stage for a better chance of success rather than following the generalized regulatory requirements. This project looked at three freezeback landfills as case studies and evaluated the final cover design of the first two in identifying parameters that lead to success in reaching and maintaining freezeback status. The parameters and research on permafrost are then applied to the third case study in a series of recommendations for consideration when designing a final cover strategy.
    • To pup or not to pup? Using physiology and dive behavior to answer the Weddell Seal's overwinter question

      Shero, Michelle R.; Mellish, Jo-Ann; Burns, Jennifer; Hardy, Sarah; Costa, Daniel; Buck, C. Loren (2015-08)
      Female Weddell seals (Leptonychotes weddellii) haul-out on the fast-ice surrounding the Antarctic continent in October and November each year to give birth to and nurse their pups. Breeding follows directly after weaning (December) and the annual molt begins in January-February. Animals reduce foraging efforts during the lactation and molting periods, but very little is known regarding the influence of this reduced activity on physiological condition. After a period of embryonic diapause, the annual molt coincides with embryo attachment and the start of active gestation. Consequently, female physiological condition at this time may influence reproductive success the following year. Overall female health and the ability to forage successfully throughout the gestation period (austral winter) may impact the likelihood that a pregnancy is brought to term. Therefore, this study tested whether overwinter changes in Weddell seal physiology and foraging efforts are reflected in reproductive outcomes the following year (i.e., to answer the over winter question of "to pup or not to pup?"). From 2010-2012, 100 (January-February: n = 53; October-November: n = 47) adult female Weddell seals were captured in Erebus Bay, Antarctica to assess overwinter changes in physiological condition and/or dive behavior that may be associated with reproductive success. Morphometric measurements and isotopic dilution procedures revealed that female Weddell seals gain ~10-15% of their body mass across the winter period, primarily in the form of blubber and lipid mass. The proportion of mass and lipid gain was similar regardless of whether females returned the following year and successfully gave birth, or did not produce a pup. Further, the amount of mass and energy acquired across gestation in the Weddell seal was markedly less than previously reported for other phocid species. Despite changes in activity patterns and body composition, Weddell seals maintained blood hemoglobin and muscle myoglobin concentrations across the winter. Therefore, Weddell seal total body oxygen stores and calculated aerobic dive limit (cADL) were conserved. This ensures that females have the physiological capabilities to effectively forage directly following the annual molt when they are at their leanest and must regain body mass and lipid stores. Although aerobic capacities did not change, dive effort varied considerably throughout the austral winter. Proxies of dive effort (duration, depth, %dives > cADL) were highest just after the molt (January-February) and just prior to the subsequent pupping season (August-September). Additionally, the proportion of each day spent diving increased mid-winter. Females that were observed the following year with a pup significantly increased all indices of foraging effort during the austral winter as compared to females that returned without a pup. This study is the first to identify and measure differences in dive efforts due to reproductive status, and indicates that successful reproduction is associated with greater foraging effort.