1. Antarctic krill (Euphausia superba) form aggregations known as swarms that vary greatly in size and density. Six acoustic surveys were conducted as part of multidisciplinary studies at two study sites, the western and eastern core boxes (WCB and ECB), during the 1997, 1998 and 1999 austral summers, at South Georgia. A quantitative, automated, image processing algorithm was used to identify swarms, and calculate swarm descriptors, or metrics. In contrast to acoustic surveys of aggregations of other pelagic species, a strong correlation (r = 0.88, p = 0.02, 95% C.I.= 0.24 to 0.99) between the number of krill swarms and the mean areal krill density [rho.hat] was found. Multivariate analysis was used to partition swarms into three types, based on contrasting morphological and internal krill density parameters. Swarm types were distributed differently between inter-surveys and between on and off-shelf regions. This swarm type variation has implications for krill predators, by causing spatial heterogeneity in swarm detectability, suggesting that for optimal foraging to occur, predators must engage in some sort of adaptive foraging strategy. 2. Krill predator-prey interactions were found to occur at multiple spatial and temporal scales, in a nested, or hierarchical structure. At the largest inter-survey scale, an index of variability, I, was developed to compare variation in survey-scale predator sightings, sea temperature and [rho.hat]. Using I and a two-way ANOVA, core box, rather than year, was found to be a more important factor in determining species distribution. The absence of Blue-petrels (Halobaena caerulea) and the elevated number of Antarctic fur seals (Arctocephalus gazella) suggest that 1998 was a characterised by colder than average water surrounding South Georgia, and a high [rho.hat] in the ECB. At the smaller, intra-survey scales (<80 km, <5 day), the characteristic scale (distances in which predator group size, or krill density were similar, L_s) were determined. For krill and predators L_s varied by survey and the L_s of krill also varied by depth within a survey. Overlap in L_s were stronger between predator species than between a predator species and krill, indicating predators were taking foraging cues from the activity of predators, rather than from the underlying krill distribution. No relationship was found between swarm characteristics and predator activity, suggesting either there is no relationship between krill swarms and predators, or that the predator and acoustic observation techniques may not be appropriate to detect such a relationship. 3. To overcome the 2-D sampling limitations of conventional echosounders, a multibeam echosounder (MBE) observed entire swarms in three-dimensions. Swarms found in the nearshore environment of Livingston Island situated in the South Shetland Islands, exhibited only a narrow range of surface area to volume ratios or roughnesses (R = 3.3, CV = 0.23), suggesting that krill adopt a consistent group behaviour to maintain swarm shape. Generalized additive models (GAM) suggested that the presence of air-breathing predators influenced the shape of a krill swarm (R decreased in the presence of predators: the swarm became more spherical). A 2D distance sampling framework was used to estimate the abundance, N, and associated variance of krill swarms. This technique took into account angular and range detectability (half-normal, [sigma_r.hat] = 365.00 m, CV = 0.16) and determined the vertical distribution of krill swarms to be best approximated by a beta-distribution ([alpha.hat] = 2.62, [CV.hat] = 0.19; [beta.hat] = 2.41, [CV.hat] = 0.15), giving the abundance of swarms in survey region as [N.hat] = 5,062 ([CV.hat] = 0.35). This research represents a substantial contribution to developing estimation of pelagic biomass using MBEs. 4. When using a single- or split-beam missing pings occur when the transmit or receive cycles are interrupted, often by aeration of the water column, under the echosounder transducer during rough weather. A thin-plate regression spline based approach was used to model the missing krill data, with knots chosen using a branch and bound algorithm. This method performs well for acoustic observations of krill swarms where data are tightly clustered and change rapidly. For these data the technique outperformed the standard MGCV GAM, and the technique is applicable for estimating acoustically derived biomass from line transect surveys.

Distance sampling and spatial capture-recapture are statistical methods to estimate the number of animals in a wild population based on encounters between these animals and scientific detectors. Both methods estimate the probability an animal is detected during a survey, but do not explicitly model animal movement. The primary challenge is that animal movement in these surveys is unobserved; one must average over all possible paths each animal could have travelled during the survey. In this thesis, a general statistical model, with distance sampling and spatial capture-recapture as special cases, is presented that explicitly incorporates animal movement. An efficient algorithm to integrate over all possible movement paths, based on quadrature and hidden Markov modelling, is given to overcome the computational obstacles. For distance sampling, simulation studies and case studies show that incorporating animal movement can reduce the bias in estimated abundance found in conventional models and expand application of distance sampling to surveys that violate the assumption of no animal movement. For spatial capture-recapture, continuous-time encounter records are used to make detailed inference on where animals spend their time during the survey. In surveys conducted in discrete occasions, maximum likelihood models that allow for mobile activity centres are presented to account for transience, dispersal, and heterogeneous space use. These methods provide an alternative when animal movement causes bias in standard methods and the opportunity to gain richer inference on how animals move, where they spend their time, and how they interact.

No description available.

The submitted work compares results of two forest inventories conducted on the plot of 200 ha within the forestry concession in the tropical rainforest in the Peruvian Amazon. First inventory conducted in 2007 used for field data collection the common method with tapes and mechanical compasses. The second inventory conducted in 2008 used a set of electronic devices, consisting of a field computer, laser rangefinder, electronic compass, a GPS unit and a specialized software Field-Map. In both inventories the positions of all trees with a dbh bigger or equal 400 mm were mapped and following attributes were recorded: position, species, total height, trunk height and dbh. Significant differences were discovered between both methods and the inadequacies were described. The results from the comparison study show that the method conducted using electronic devices is faster and more exact in measurement of tree attributes and in navigation on the plot. However, nor use of this method encompassed to map all the trees and that is why the distance sampling method for population density estimation was used for completion of inventory results. The population map of big trees was created and used for inventory simulations using circular and belt plots of different size and different density with the aim to find most suitable variants. Results of simulated inventories were evaluated regarding their accuracy and time expenses and the variants suitable for use in the zone were suggested.

The Puerto Rican Nightjar Caprimulgus noctitherus is an endangered species found in forest of southern Puerto Rico. I documented density of nightjars in Guánica Forest, the region of Guayanilla-Peñuelas, and Susúa Forest. The geographic range of the species was expanded because of this study and presence documented in a number of new localities. Stand level habitat model indicated forest type and midstory visual obscurity best predicted nightjar habitat. Landscape model predicted considerably more suitable nightjar habitat exists than had been previously estimated (> 30%) and highlighted several areas of importance for the species. I evaluated nightjar population estimation techniques and found use of point transects with lures (playback) and moon phase covariates generated best estimates. My results highlighted several sites currently under private ownership that should be protected or acquired. Establishment of new protected areas for the nightjar represents highest priority for conservation and eventual delisting of the species.

Gopher tortoise (Gopherus polyphemus; hereinafter, tortoise) is listed as threatened under the Endangered Species Act in the western portion of its range. Across the species’ range, approximately 70 % of potential habitat is privately owned, and these properties are often managed primarily for timber production. However, tortoise ecology on private, working forest landscapes remains poorly understood. To provide a better understanding of tortoise response to active forest management, I evaluated population demographics, movement ecology, and habitat selection of two tortoise populations: former Ben’s Creek Wildlife Management Area (BC) in Washington Parish, Louisiana and Perry County Gopher Tortoise Management Unit (PCGTMU) in Perry County, Mississippi. At BC, tortoises were generally clustered along utility rights-of- way and roadways. At PCGTMU, tortoises were clustered within forest stands with high quality soils. Low recruitment has been documented at BC for the last 25 years. However, PCGTMU appears to have a stable population with active recruitment.

The Sierra Madre Occidental and neighboring Madrean Sky Islands span a large and biologically diverse region of northwest Mexico and portions of the southwestern United States. Little is known about the abundance and habitat use of breeding birds in this region of Mexico, but such information is important for guiding conservation and management. We assessed densities and habitat relationships of breeding birds across Sky Island mountain ranges in Mexico and adjacent portions of the Sierra Madre from 2009 to 2012. We estimated densities at multiple spatial scales, assessed variation in densities among all major montane vegetation communities, and identified and estimated the effects of important habitat attributes on local densities. Regional density estimates of 65% of 72 focal species varied significantly among eight montane vegetation communities that ranged from oak savannah and woodland at low elevations to pine and mixed-conifer forest at high elevations. Greater proportions of species occurred at peak densities or were relatively restricted to mixed-conifer forest and montane riparian vegetation likely because of higher levels of structural or floristic diversity in those communities, but those species were typically rare or uncommon in the Sky Islands. Fewer species had peak densities in oak and pine-oak woodland, and species associated with those communities were often more abundant across the region. Habitat models often included the effects of broadleaf deciduous vegetation cover (30% of species), which, together with tree density and fire severity, had positive effects on densities and suggest ways for managers to augment and conserve populations. Such patterns combined with greater threats to high-elevation conifer forest and riparian areas underscore their value for conservation. Significant populations of many breeding bird species, including some that are of concern or were not known to occur regionally or in mountain ranges we surveyed, highlight the importance of conservation efforts in this area of Mexico.

White-tailed deer (Odocoileus virginianus) commonly consume row crops, with yield losses often attributed to their browsing. Deer density and field morphology may predict yield losses within local areas. We sought to 1) determine the effects of deer browsing on corn and soybean yields and investigate if deer density or field morphology correlated to yield loss in western Kentucky, and 2) compare pellet-based distance sampling to game camera surveys to determine if a distance sampling technique could accurately estimate deer density during the growing season. Overall, deer reduced corn and soybean yields on one-half of surveyed properties. Deer density did not influence yield losses in either crop; however, field morphology correlated with soybean yield losses. Pellet-based distance sampling provided statistically similar estimates as our game camera survey technique; however, at the individual farm level distance sampling estimates proved unreliable. Inaccurate model parameter (i.e., defecation rates) and inability to detect pellet groups in dense vegetation complicated the reliability of distance sampling models. Overall, yield losses from deer occur in western Kentucky and may be a localized event. Finally, game camera surveys should be used over pellet-based distance sampling during the growing season until detection issues and inaccurate model parameters are solved.

Wildlife management deals with problems concerning sustainable harvest, conservation of threatened species and adjustment of wildlife populations to levels acceptable to for instance forestry, agriculture, traffic and conservation interests. A detailed knowledge of the population is then required. It is therefore important to develop reliable and cost-efficient survey methods. The purpose of this study was to test the distance sampling method where objects are observed while walking along a line, as a way of counting deer pellet groups and to compare the results with ordinary plot surveys. The inventory speed for distance sampling increases with increasing amount of droppings/km2. The amount of droppings seems to have little or no effect on the inventory speed of the plot survey method. Therefore the plot survey method could be a better alternative than the distance sampling method when the densities of droppings are high and vice versa. When comparing the two methods estimates of animal densities with data (orally) from game managers based on other surveys and flying observations and estimations in the different areas, both methods showed too low density for red deer in Valinge. This indicates that the supplementary feeding seem to have an effect on the results of red deer density for both methods.

<p>Wildlife management deals with problems concerning sustainable harvest, conservation of threatened species and adjustment of wildlife populations to levels acceptable to for instance forestry, agriculture, traffic and conservation interests. A detailed knowledge of the population is then required. It is therefore important to develop reliable and cost-efficient survey methods.</p><p>The purpose of this study was to test the distance sampling method where objects are observed while walking along a line, as a way of counting deer pellet groups and to compare the results with ordinary plot surveys.</p><p>The inventory speed for distance sampling increases with increasing amount of droppings/km2. The amount of droppings seems to have little or no effect on the inventory speed of the plot survey method. Therefore the plot survey method could be a better alternative than the distance sampling method when the densities of droppings are high and vice versa.</p><p>When comparing the two methods estimates of animal densities with data (orally) from game managers based on other surveys and flying observations and estimations in the different areas, both methods showed too low density for red deer in Valinge. This indicates that the supplementary feeding seem to have an effect on the results of red deer density for both methods.</p>