INTRODUCTION: Coupling in the distal foot may be due, at least in part, to the foot's windlass mechanism. This mechanism has been demonstrated passively, but its role in dynamic movement is still unclear. A systematic manipulation of metatarsophalangeal (MTP) mechanics may help determine to what extent distal foot coupling during dynamic and active movement is due to the windlass mechanism versus active muscle contractions or springlike ligaments. Furthermore, exploring the windlass mechanism in feet with varying foot structure may aid our understanding of the relationship between foot structure and foot function. PURPOSE: The overall purpose of this study is to investigate the kinematic and kinetic coupling between the MTP and midtarsal joints through a systematic manipulation of the windlass mechanism (achieved through methodical changes to MTP motion). Additionally, we aimed to explore the relationship between foot structure and the efficacy of the windlass mechanism during passive, active, and dynamic movement. METHODS: First, arch height and flexibility were measured using the Arch Height Index Measurement System. Next, participants performed four order-randomized conditions where MTP extension was isolated: 1) Seated Passive MTP Extension, 2) Seated Active MTP Extension, 3) Standing Passive MTP Extension, and 4) Standing Active MTP Extension. Lastly, participants performed three heel raise conditions that manipulated the starting position of the MTP joint: 1) Neutral: normal heel raise, 2) ToeExt: heel raise with the toes placed on an inclined surface of 30 degrees to put the MTP joint into extension, and 3) ToeFlex: heel raise with the toes placed on a declined surface of 30 degrees to put the MTP joint into flexion. All conditions were performed to a metronome of 40 beats per minute to control angular velocity. A kinetic multisegment foot model was created in Visual 3D software and used to calculate ankle, midtarsal, and MTP joint angles, moments, powers, and work. RESULTS: Kinematic coupling was approximately six times greater in the heel raise conditions compared to the isolated MTP extension conditions and suggests that the windlass mechanism only plays a small role in dynamic tasks. This is likely due to the greater involvement of active muscle contractions during heel raises. As the starting position of the MTP joint became increasingly extended, the amount of negative work at the MTP joint increased concomitantly with increased positive work done at the midtarsal joint, while net distal-to-hindfoot work remained unchanged. Our combined results suggest that there is substantial coupling within the distal foot, but this coupling is likely attributed to more than simple passive energy transfer from the windlass mechanism. Future investigations into the intrinsic foot muscle activation and biarticular muscle effects are likely needed to determine the source of this coupling. Lastly, the relationship between foot structure and function is still unclear and our results suggest that arch height or arch flexibility alone may not be adequate predictors of dynamic foot function.

Diet of cougars (Felis concolor) was studied from December 1978 to August 1981, on a 4500 km2 study area near Escalante, Utah. Prey eaten was determined from analysis of 112 animals consumed as prey, and from 239 cougar scats. Mule deer (Odocoileus hemionus) were the major prey item, comprising 81% of biomass consumed. Lagomorphs, large rodents, and smaller predators were also important components. Cattle comprised Motion-sensitive radio-transmitters were placed on 15 cougars, from 3 months to 7-9 years of age. Three parameters of the radio signal were used to determine activity levels during 6843 1-minute sampling periods: number of changes in pulse rate, predominant pulse mode, and signal integrity, based on 308 minutes of "known" acti vity. Cougars showed distinct crepuscular (sunrise, sunset ± 2 hrs) activity peaks (P Estimates of energetic costs of basal metabolism, and of activity, growth, and reproduction were used in a predictive model of energy cost of free-existence. Information on dietary composition, live weight and energy content of prey animals, and assimilation efficiencies were used to provide estimates of the frequency at which deer were killed (deer/day) and consumed (kg/day). Single adults were estimated to kill 1 deer per 8-16 days. Females with 3 large cubs would kill 1 deer as often as every 2-3 days. A known population of 8 adult cougars was predicted to consume 417 deer per year.

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Because little is known about juvenile American White Pelicans (Pelecanus erythrorhynchos) this study was conducted to gather more information on disease, general ecology and growth of American White Pelicans from hatching to fledging. In July 2011, American White Pelican regurgitate samples from North and South Dakota sub-colonies were collected/analyzed in preparation for a captive trial. Nutrient content compared between the colonies was found to be significantly different. Concentrations of Immunoglobulin Y and A in regurgitate samples were significantly different between colonies. A captive trial began 29 May 2012 and ended 30 July 2012, in which 16 American White Pelicans were hand raised from hatching to fledging. During the captive trial, various growth parameters, intake and fecal output were examined to determine the effect of the parasite Bolbophorus damnificus in 8 infected and 8 non-infected (parasite free) pelicans. Growth data collected on B. damnificus infected (n = 8) American White Pelicans was compared to previously mentioned parasiteree pelicans (n = 8) to determine effects of the parasite. There were no differences between groups for culmen length (P= 0.214), tarsal length (P = 0.306), body weight (P = 0.884) or intake (P = 0.963). There was also no effect of the parasite on body temperature. Towards the end of the captive trial, several pelicans both on (n = 16) and off (n = 11) trial became naturally infected with West Nile Virus. Clinical symptoms ranged from lethargy and/or wing droop to total paralysis. Progression of disease is detailed in two well-defined case studies with additional information included on clinical signs, physiological parameters, and a review of the pathology of disease for other infected birds.

Moist-soil wetlands that are seasonally flooded provide important habitats for waterfowl in the Mississippi Alluvial Valley (MAV). These wetlands often contain tall and dense vegetation that may constrain waterfowl use before natural openings form. During winters 2006–2009, I estimated abundances of waterbirds, seeds and tubers, and invertebrates in response to autumn, prelooding treatments of light disking, mowing, and no manipulation (control) of vegetation in 26 moist-soil wetlands in the MAV. Seeds and tubers were most abundant in control and mowed plots in late autumn. Decomposition was least and invertebrate abundance was greatest in control plots during winter. Dabbling ducks were most abundant in mowed and disked plots during winter. Lightly disked plots contained ~30% fewer seeds and tubers than mowed and control plots. In late winter, ~260 kg[dry]/ha of seeds and tubers remained among mowed, disked, and control plots. Therefore, autumn mowing of robust moist-soil vegetation can be used to create an interspersion of emergent vegetation and open water attractive to waterfowl and conserve waterfowl foods. Additionally, I identified 6 seed taxa that may not be used for food by dabbling ducks (i.e., Amaranthus spp., Cyperus odoratus, Eleocharis spp., Ipomoea spp., Jacquemontia tamnifolia, Sesbania herbacea) and estimated that removing these and other taxa not reported in diet literature in the MAV resulted in a ~31% reduction in estimated moist-soil food availability for ducks. In other experiments, I estimated that waterfowl reduced experimentally placed Japanese millet (Echinochloa frumentacea) to ~10 kg/ha and other natural seeds and tubers to ~170 kg/ha in experimental plots in mid-winter. However, waterfowl did not abandon wetlands or stop foraging when seed reduction ceased, suggesting residual abundances of seeds and tubers represented a food availability threshold (FAT). Using the median FAT value of 220 kg/ha from both experiments and removing 31% of seed mass that may not be consumed by dabbling ducks, results in a ~70% decrease in moist-soil seed availability in the MAV. Conservation planners should consider reducing the current estimates of seed and tuber availability and recommend increasing active management or implementation of additional managed, moist-soil wetlands in the MAV.

Endotherms living in cold environments must pay the energetic cost of maintaining a high core body temperature. This cost can be potentially alleviated by an important yet often overlooked mechanism: “activity-thermoregulatory heat substitution” (i.e., the use of the heat generated by active skeletal muscles to replace heat that would have been generated by thermogenesis). While substitution has been documented numerous times, the extent of individual variation in substitution has never been quantified. I used a respirometry cage system to repeatedly measure substitution through the concomitant monitoring of metabolic rate (MR) and locomotor activity in 46 female white-footed mice (Peromyscus leucopus) in neutral and cold ambient temperatures. I took a total of 117 measures of substitution by quantifying the difference in the slope of the relationship between MR and locomotor activity speed at two different ambient temperatures. Consistency repeatability (±se) of substitution was 0.313±0.131 – hence, about a third of the variation in substitution occurs at the among-individual level. Including key morphological traits such as trunk surface area, tail mass, heart mass, and body length accounted for the majority of the among-individual variation, suggesting that I have successfully identified traits underlying individual differences in substitution. Overall, my results show that substitution is repeatable and hence might potentially be subject to selection. Future studies should test if substitution conveys fitness advantages directly (by providing energetically cheaper activity which in turn can be utilized for reproduction), or indirectly (i.e., driven by individual differences in morphology). Future studies should also test if there is a trade-off between substitution and dry heat transfer (a thermoregulatory mechanism essential for preventing hyperthermia).

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