Analysis of finite population surveys : sample size and testing considerations

This dissertation concerns two topics in the analysis of finite population surveys: setting sample size and hypothesis testing. The first concerns the a priori determination of the sample size needed to obtain species members. The second concerns testing distributional hypotheses when two equal-size populations are sampled. Setting sample size to obtain species is a problem which arises when an investigator wants to obtain (1) a member of all species present in an area (2) a member of all species whose relative frequency is greater than, say, 20% or (3) a member of each species in a target set of species. Chapter 2 presents a practical solution to these questions by setting a target sample size for which the species are obtained with known probability. The solution requires the estimated relative frequency of the rarest species of interest; total number of species is not needed. Because this problem has substantial computational demands, easy-to-compute formulas are needed and given. Three practical examples are presented. Testing of finite population distributional hypotheses is covered in Chapter 3. The test proposed here works under reasonably general designs and is based on a Horvitz-Thompson type correction of the usual Mann-Whitney U statistic. The investigation here compared this proposed test to a corrected (for finiteness) form of the usual Wilcoxon rank sum test. Size and power of the two test procedures are investigated using simulation. The proposed test had approximately correct nominal size over a wide range of situations. The corrected Wilcoxon test exhibited extreme violations in size in many cases. Power of the two tests in situations where they have equal size is similar in most practically interesting cases

Dynamic Responses of Calving Caribou to Oilfields in Northern Alaska

Past research has suggested that during the calving period, caribou (Rangifer tarandus) in Arctic Alaska generally avoid areas within 1 km of oilfield roads with traffic. However, avoidance is not absolute, and caribou may habituate to infrastructure (e.g., buildings, roads, well pads) and human activity. We conducted road-based surveys of caribou in oilfields on Alaska’s Arctic Coastal Plain during the late calving and post-calving periods of June in 2000–02. We recorded location, composition, and behavior of caribou groups located less than 1 km from active gravel roads and production pads. Caribou groups with calves were on average distributed farther from oilfield infrastructure than were groups without calves, but habituation to oilfield activities, indicated by decreased avoidance, occurred at similar rates for groups with and without calves. During the calving period, sighting rates were greater in areas of low human activity, and calf percentages tended to be greater at night when oilfield activity was reduced. Caribou groups were on average closer to infrastructure during the post-calving periods than during the calving periods in 2000 and 2001, but not in 2002. In 2002, when snow melted early, caribou groups were closer to infrastructure during the calving period than in 2000 and 2001, when snow melted later, emphasizing the importance of examining environmental variables when investigating the dynamic interactions of caribou and oilfields. Overall, caribou appeared to habituate to active oilfield infrastructure after the calving period in 2000, late in the calving period in 2001, and likely before our sampling period in 2002. The timing of annual rehabituation was positively correlated with timing of spring snowmelt. Land and wildlife managers can use information from this study to develop calving period-specific mitigation measures that are more effective and flexible.Selon des recherches antérieures, pendant sa période de vêlage, le caribou (Rangifer tarandus) de l’Alaska arctique évite généralement les régions se trouvant à l’intérieur d’un kilomètre des routes où circulent des véhicules menant aux chantiers pétroliers. Cependant, cet évitement n’est pas absolu, et le caribou peut s’accoutumer aux infrastructures (comme les bâtiments, les routes et les chantiers) et à l’activité humaine. Nous avons effectué le dénombrement des caribous près des routes des champs de pétrole de la plaine côtière arctique de l’Alaska vers la fin de la période de vêlage et après la période de vêlage de juin 2000 à 2002. Nous avons consigné l’emplacement, la composition et le comportement des groupes de caribous se trouvant à moins d’un kilomètre des routes de gravier et des chantiers de production en activité. En moyenne, les caribous qui avaient des petits se tenaient plus loin des infrastructures pétrolières que les groupes de caribous qui n’avaient pas de petits. Cela dit, l’accoutumance aux activités pétrolières, dénotée par un moins grand évitement, survenait à des taux semblables pour les groupes qui avaient des petits et les groupes qui n’en avaient pas. Pendant la période de vêlage, les taux d’observation de caribous étaient plus élevés dans les régions où il y avait peu d’activité humaine, et les pourcentages de petits avaient tendance à être plus élevés la nuit, lorsqu’il y avait peu de va-et-vient aux chantiers. En moyenne, les groupes de caribous s’approchaient plus des infrastructures pendant les périodes suivant le vêlage des années 2000 et 2001, mais pas en 2002. En 2002, quand la neige a fondu plus tôt que d’habitude, les groupes de caribous s’approchaient plus des infrastructures pendant la période de vêlage qu’en 2000 et 2001, lorsque la neige a fondu plus tard. Cela fait ressortir l’importance de tenir compte des variables environnementales lorsque nous faisons des enquêtes sur les interactions dynamiques entre les caribous et les champs de pétrole. Dans l’ensemble, les caribous semblaient s’accoutumer aux infrastructures pétrolières en activité après la période de vêlage en 2000, puis vers la fin de la période de vêlage en 2001, et vraisemblablement avant notre période d’échantillonnage en 2002. Le moment de l’accoutumance annuelle coïncidait positivement avec le moment de la fonte des neiges au printemps. Les gestionnaires des terres et de la faune peuvent se servir de l’information émanant de cette étude pour élaborer des mesures d’atténuation tenant compte de la période de vêlage, mesures qui sont plus efficaces et qui présentent plus de souplesse

Fish Bulletin 180. California Coastal Salmonid Population Monitoring: Strategy, Design, and Methods

California’s salmon and steelhead populations have experienced marked declines leading to listing of almost all of California’s anadromous salmonids under the California Endangered Species Act (CESA) and Federal Endan-gered Species Act (ESA). Both CESA and ESA listings require recovery plans that call for monitoring to provide some measure of progress toward recovery. In addition, there are related monitoring needs for other management activi-ties such as hatchery operations and fisheries management

Caribou Distribution During the Post-calving Period in Relation to Infrastructure in the Prudhoe Bay Oil Field, Alaska

There is concern that caribou (Rangifer tarandus) may avoid roads and facilities (i.e. infrastructure) in the Prudhoe Bay oil field (PBOF) in northern Alaska, and that this avoidance can have negative effects on the animals. We quantified the relationship between caribou distribution and PBOF infrastructure during the post-calving period (mid-June to mid-August) with aerial surveys from 1990 to 1995. We conducted four to eight surveys per year with complete coverage of the PBOF. We identified active oil field infrastructure and used a geographic information system (GIS) to construct ten 1 km wide concentric intervals surrounding the infrastructure. We tested whether caribou distribution is related to distance from infrastructure with a chi-squared habitat utilization-availability analysis and log-linear regression. We considered bull, calves, and total caribou of all sex/age classes separately. The habitat utilization-availability analysis indicated there was no consistent trend of attraction to or avoidance of infrastructure. Caribou frequently were more abundant than expected in the intervals close to infrastructure, and this trend was more pronounced for bulls and for total caribou of all sex/age classes than for calves. Log-linear regression (with Poisson error structure) of numbers of caribou and distance from infrastructure were also done, with and without combining data into the 1 km distance intervals. The analysis without intervals revealed no relationship between caribou distribution and distance from oil field infrastructure, or between caribou distribution and Julian date, year, or distance from the Beaufort Sea coast. The log-linear regression with caribou combined into distance intervals showed the density of bulls and total caribou of all sex/age classes declined with distance from infrastructure. Our results indicate that during the post-calving period: 1) caribou distribution is largely unrelated to distance from infrastructure; 2) caribou regularly use habitats in the PBOF; 3) caribou often occur close to infrastructure; and 4) caribou do not appear to avoid oil field infrastructure.On s'inquiète du fait que le caribou (Rangifer tarandus) pourrait éviter les routes et installations (c-à-d. les infrastructures) du champ pétrolifère de Prudhoe Bay dans l'Alaska septentrional et que ce comportement pourrait avoir des répercussions négatives sur les animaux. Des relevés aériens effectués de 1990 à 1995 ont permis de quantifier le rapport entre la distribution du caribou et les infrastructures du champ pétrolifère de Prudhoe Bay au cours de la période suivant immédiatement la mise bas (de mi-juin à mi-août). On a procédé à un nombre de relevés annuels allant de quatre à huit, couvrant toute la superficie du champ. On a identifié les infrastructures du champ pétrolifère qui étaient en activité et utilisé un système d'information géographique (SIG) pour construire dix anneaux concentriques de 1 km de large entourant chaque infrastructure. On a testé l'hypothèse que la distribution du caribou est indépendante de l'éloignement de l'infrastructure grâce au test de chi carré entre l'utilisation et la disponibilité de l'habitat, et à la régression log-linéaire. On a tenu compte séparément de la catégorie des mâles, de celle des veaux et de celle de la population totale, sexe et âge confondus. L'analyse de l'utilisation et de la disponibilité de l'habitat révélait qu'il n'y avait pas de schéma cohérent d'attrait ou d'évitement des infrastructures. Les caribous étaient souvent plus abondants que prévu dans les anneaux proches des infrastructures, et cette tendance était plus prononcée pour les mâles adultes et pour l'ensemble des catégories, sexe et âge confondus, que pour les veaux. On a fait les analyses par régression log-linéaire en regroupant et sans regrouper les données anneaux de 1 km de largeur. L'analyse sans regroupement montrait qu'il n'existe pas de rapport entre la distribution du caribou et l'éloignement des infrastructures du champ pétrolifère, ou entre la distribution du caribou et la date julienne ou même l'éloignement de la côte de la mer de Beaufort. L'analyse log-linéaire avec les caribous regroupés dans des anneaux concentriques montrait que la densité des mâles adultes de l'ensemble de la population, sexe et âge confondus, était plus élevée dans les anneaux jouxtant les infrastructures. Nos résultats indiquent que, durant la période suivant immédiatement la mise bas: (1) la distribution du caribou est dans une large mesure indépendante de l'éloignement des infrastructures; (2) le caribou utilise les habitats au sein du champ pétrolifère de Prudhoe Bay sur une base régulière; (3) le caribou se trouve fréquemment près des infrastructures; et (4) le caribou ne semble pas chercher à éviter les infrastructures du champ pétrolifère

Behavioural responses of western gray whales to a 4-D seismic survey off northeastern Sakhalin Island, Russia

A seismic survey was conducted off the northeastern coast of Sakhalin Island, Russia in 2010. The survey area was adjacent to the only known near-shore feeding ground of the Critically Endangered population of western gray whales Eschrichtius robustus in the western Pacific south of the Aleutian Islands. This study examined the effectiveness of efforts to minimize the behavioural responses of the whales to vessel proximity and sound during the survey. Two shore-based behavioural observation teams monitored whale movements and respirations pre-, during and post-seismic survey. Theodolite tracking and focal-animal follow methods were used to collect behavioural data. Mixed linear models were used to examine deviations from 'normal' patterns in 10 movement and 7 respiration response variables in relation to vessel proximity, vessel/ whale relative orientations and 8 received sound metrics to examine if seismic survey sound and/or vessel activity influenced the whales' behaviour. Behavioural state and water depth were the best 'natural' predictors of whale movements and respiration. After considering natural variation, none of the response variables were significantly associated with seismic survey or vessel sounds. A whale's distance from shore and its orientation relative to the closest vessel were found to be significantly influenced by vessel proximity, which suggested some non-sound related disturbance. The lack of evidence that the whales responded to seismic survey sound and vessel traffic by changing either their movement or respiration patterns could indicate that the current mitigation strategy is effective. However, power analyses suggest that our sample sizes were too small to detect subtle to moderate changes in gray whale behaviour

Survival, density, and abundance of common bottlenose dolphins in Barataria Bay (USA) following the Deepwater Horizon oil spill

To assess potential impacts of the Deepwater Horizon oil spill in April 2010, we conducted boat-based photo-identification surveys for common bottlenose dolphins Tursiops truncatus in Barataria Bay, Louisiana, USA (~230 km2, located 167 km WNW of the spill center). Crews logged 838 h of survey effort along pre-defined routes on 10 occasions between late June 2010 and early May 2014. We applied a previously unpublished spatial version of the robust design capture-recapture model to estimate survival and density. This model used photo locations to estimate density in the absence of study area boundaries and to separate mortality from permanent emigration. To estimate abundance, we applied density estimates to saltwater (salinity > ~8 ppt) areas of the bay where telemetry data suggested that dolphins reside. Annual dolphin survival varied between 0.80 and 0.85 (95% CIs varied from 0.77 to 0.90) over 3 yr following the Deepwater Horizon spill. In 2 non-oiled bays (in Florida and North Carolina), historic survival averages approximately 0.95. From June to November 2010, abundance increased from 1300 (95% CI ± ~130) to 3100 (95% CI ± ~400), then declined and remained between ~1600 and ~2400 individuals until spring 2013. In fall 2013 and spring 2014, abundance increased again to approximately 3100 individuals. Dolphin abundance prior to the spill was unknown, but we hypothesize that some dolphins moved out of the sampled area, probably northward into marshes, prior to initiation of our surveys in late June 2010, and later immigrated back into the sampled area.Publisher PDFPeer reviewe

Моделирование формирования структуры металломатричных композитов в процессе синтеза с оценкой эффективных свойств

Работа посвящена моделированию процесса кристаллизации композита с металлической матрицей и твердыми включениями с учетом условий синтеза (давление, скорость охлаждения), моделированию процесса формирования переходной зоны между частицами и матрицей и расчету эффективных свойств получаемых композитов.The work is devoted to modeling the crystallization process of metal matrix composite with solid inclusions, taking into account the synthesis conditions (pressure, cooling rate), to modeling the formation of the transition zone between particles and matrix, and calculating the effective properties of the resulting composites

First Neutrino Observations from the Sudbury Neutrino Observatory

The first neutrino observations from the Sudbury Neutrino Observatory are presented from preliminary analyses. Based on energy, direction and location, the data in the region of interest appear to be dominated by 8B solar neutrinos, detected by the charged current reaction on deuterium and elastic scattering from electrons, with very little background. Measurements of radioactive backgrounds indicate that the measurement of all active neutrino types via the neutral current reaction on deuterium will be possible with small systematic uncertainties. Quantitative results for the fluxes observed with these reactions will be provided when further calibrations have been completed.Comment: Latex, 7 pages, 10 figures, Invited paper at Neutrino 2000 Conference, Sudbury, Canada, June 16-21, 2000 to be published in the Proceeding

Invader removal triggers competitive release in a threatened avian predator

Changes in the distribution and abundance of invasive species can have far-reaching ecological consequences. Programs to control invaders are common but gauging the effectiveness of such programs using carefully controlled, large-scale field experiments is rare, especially at higher trophic levels. Experimental manipulations coupled with long-term demographic monitoring can reveal the mechanistic underpinnings of interspecific competition among apex predators and suggest mitigation options for invasive species. We used a large-scale before-after control-impact removal experiment to investigate the effects of an invasive competitor, the barred owl (Strix varia), on the population dynamics of an iconic old-forest native species, the northern spotted owl (Strix occidentalis caurina). Removal of barred owls had a strong, positive effect on survival of sympatric spotted owls and a weaker but positive effect on spotted owl dispersal and recruitment. After removals, the estimated mean annual rate of population change for spotted owls stabilized in areas with removals (0.2% decline per year), but continued to decline sharply in areas without removals (12.1% decline per year). The results demonstrated that the most substantial changes in population dynamics of northern spotted owls over the past two decades were associated with the invasion, population expansion, and subsequent removal of barred owls. Our study provides experimental evidence of the demographic consequences of competitive release, where a threatened avian predator was freed from restrictions imposed on its population dynamics with the removal of a competitively dominant invasive species

Demographic response of northern spotted owls to barred owl removal

Federally listed as threatened in 1990 primarily because of habitat loss, the northern spotted owl (Strix occidentalis caurina) has continued to decline despite conservation efforts resulting in forested habitat being reserved throughout its range. Recently, there is growing evidence the congeneric invasive barred owl (Strix varia) may be responsible for the continued decline primarily by excluding spotted owls from their preferred habitat. We used a long-term demographic study for spotted owls in coastal northern California as the basis for a pilot barred owl removal experiment. Our demography study used capture–recapture, reproductive output, and territory occupancy data collected from 1990 to 2013 to evaluate trends in vital rates and populations. We used a classic before-after-control-impact (BACI) experimental design to investigate the demographic response of northern spotted owls to the lethal removal of barred owls. According to the best 2-species dynamic occupancy model, there was no evidence of differences in barred or northern spotted owl occupancy prior to the initiation of the treatment (barred owl removal). After treatment, barred owl occupancy was lower in the treated relative to the untreated areas and spotted owl occupancy was higher relative to the untreated areas. Barred owl removal decreased spotted owl territory extinction rates but did not affect territory colonization rates. As a result, spotted owl occupancy increased in the treated area and continued to decline in the untreated areas. Prior to and after barred owl removal, there was no evidence that average fecundity differed on the 2 study areas. However, the greater number of occupied spotted owl sites on the treated areas resulted in greater productivity in the treated areas based on empirical counts of fledged young. Prior to removal, survival was declining at a rate of approximately 0.2% per year for treated and untreated areas. Following treatment, estimated survival was 0.859 for the treated areas and 0.822 for the untreated areas. Derived estimates of population change on both study areas showed the same general decline before removal with an estimated slope of –0.0036 per year. Following removal, the rate of population change on the treated areas increased to an average of 1.029 but decreased to an average of 0.870 on the untreated areas. The results from this first experiment demonstrated that lethal removal of barred owls allowed the recovery of northern spotted owl populations in the treated portions of our study area. If additional federally funded barred owl removal experiments provide similar results, this could be the foundation for development of a long-term conservation strategy for northern spotted owls.This is the publisher’s final pdf. The article is copyrighted by the Wildlife Society and published by John Wiley & Sons, Inc. It can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%291937-2817Keywords: barred owl, removal experiment, northern spotted owl, demography, competitio