The effects of group size on aspects of stoneloach foraging behaviour were examined in laboratory experiments. Fish were observed under dark conditions, using infra red illumination and video equipment. Experiments were timed to coincide with the stoneloach's natural time of maximum activity, immediately after a period of artificially simulated dusk. Individual stoneloach located a concealed food source more rapidly when group size was increased from one to five fish. Large quantitative differences were observed between fish, and those which were slow to locate food when alone remained poor when conspecifics were present. Over a 900 sec period, individuals in groups of five fish spent a greater proportion of available time searching, and appeared to sample the environment more, when compared with individuals in groups of only two. An increase in sampling may have counteracted the observed reduction in the number of feeding attempts by the fish in the larger groups, which resulted from the increased emphasis on searching. Groups of both six and twelve fish, foraging in tanks comprising two feeding areas each containing a patch, and a central area where no food was available, distributed themselves roughly in accordance with the predictions of an ideal free distribution when patches were equally profitable. When the patches differed in profitability in a ratio of either 2:1 or 5:1, the number of fish found in the low profitability area was as predicted. However, the number found in the high profitability area fell below that predicted, due to the presence of some individuals in the central area of the tanks. It is suggested that the latter individuals were found in the central area as a result of non-aggressive interference between individuals in the high profitability area. Finally, the marginal value theorem was used to predict the optimal patch residence time. The prediction was met in experimental tests at a group size of one, but at group sizes of two or five fish the observed time was significantly lower than that predicted.

Although deer abundance is high throughout most areas of Virginia, parts of western Virginia, especially on public lands, have comparatively low density deer populations. Concerns voiced by sportsmen regarding declining deer numbers in this region prompted interest in research to investigate the role of predation on deer populations. The coyote (Canis latrans) is a relative newcomer to Virginia, and relatively little is known about the role coyotes play in Virginia ecosystem dynamics, including their interactions with other sympatric predators. Research studies in other areas suggest that predation from coyotes, bobcats (Lynx rufus), and black bears (Ursus americanus) may be a significant source of deer (Odocoileus virginianus) mortality, especially for fawns, and the cumulative effects of predation from these sources may also increase the potential for additive mortality in deer populations. An important consideration when comparing feeding strategies of carnivores is the relative availability of food items across the landscape. I estimated the relative seasonal availability of several potential food items in a mosaic landscape that included some areas of prescribed burning and variable timber harvest in the mountains of western Virginia between June 2011 and May 2013. I focused on 4 broad categories of food items: white-tailed deer, mid-sized mammals (raccoons, Procyon lotor, opossums, Didelphis virginiana, cottontails, Sylvilagus spp., and squirrels, Sciurus spp.), small mammals, and soft mast. I used distance sampling to estimate deer density, camera trapping techniques to estimate mid-sized mammal trapping rates and occupancy, mark-recapture techniques to estimate small mammal abundance, and vegetation sampling to estimate % cover, which I used as measures of food availability for predation. To estimate carnivore diet, I analyzed scats of coyotes (n = 334), bobcats (n = 258), and black bears (n = 107) collected monthly from June 2011 and May 2013. Additionally, I compared estimates of % occurrence to estimates of seasonal availability of deer, mid-sized mammals, small mammals, and soft mast by ranking availability of food items from 0 (unavailable) to 4 (highly available) from my monthly and seasonal food item abundance and density estimates. I then ranked % occurrence in scat on a 0 - 4 scale and compared diet rankings to food item availability where changes in rank indicate differences from the generalist diet. Deer densities were substantially higher in Bath County (4.75 - 16.06 deer/km²) than in Rockingham County (0.17 - 3.55 deer/km²). I estimated availability of other food items only in Bath County. For mid-sized mammals, I estimated low activity as shown by constant, but low, trapping rates (#photo events/trap nights*100) of opossums, and relatively higher, constant trapping rates of cottontails. Raccoon and squirrel trapping rates were highly variable across seasons and raccoon occupancy (proportion of sites occupied) was higher in summer and fall (0.51 - 0.59) whereas squirrel occupancy was highest in October-November (0.51 - 0.53). Cottontail and opossum occupancies were higher in burned areas (0.40 - 0.57, 0.24 - 0.46, respectively), whereas raccoon and gray squirrel occupancies were higher in unburned areas (0.23 - 0.78, 0.12 - 0.58, respectively). Using program MARK I estimated high abundance and density of Peromyscus spp. in all seasons relative to other small mammal species. Densities of meadow voles and jumping mice were high seasonally in open field habitat. Densities of eastern chipmunks, red-backed voles, and Peromyscus spp. were significantly higher in burned areas relative to unburned sites. Among soft mast species, blueberries comprised the largest % occurrence. I expect a generalist predator to consume deer at a constant rate and have lower % deer occurrence in Rockingham County where deer densities are much lower. I expect seasonally constant, but low, occurrence of opossum and relatively higher, but similarly constant, occurrence of cottontail. I expect raccoon occurrence to be relatively high in summer and fall, and lower in winter. Squirrel occurrence should peak in October and November, followed by a steady decline until June. Based on availability, Peromyscus spp. should be the most commonly occurring small mammal in the diet of a generalist predator, rivaled by meadow voles (Clethrionomys gapperi) in fall and perhaps summer. I expect chipmunks (Tamias striatus) and red-backed voles to occur at constant but low rates in predator diets. I predict that various species of soft mast may occur during their respective fruiting seasons. Deer were the most frequently occurring food item of coyotes in all months in both counties, with % biomass consumed highest in June (Bath: 60.0 - 90.9 %; Rockingham: 55.6 - 92.3%). Deer occurrence in bobcat scat peaked in June (77.54 %). In black bear scat, deer occurrence was highest in February and March (100 %), however sample sizes in these months were extremely low (n = 2, 3 respectively). All 3 predators consumed deer more than expected in June and July. In most months, coyotes consumed deer and soft mast more often than expected (1 rank higher) and they consumed deer much higher (2-3 ranks higher) than expected in January and February. While deer was a major food item in the diets of all 3 predators, it is unclear whether this observed result was caused by predation or scavenging. It is unlikely that coyotes, bears, or bobcats are preying on adult deer with high frequency. I did not estimate the availability of deer carcasses for scavenging in this study. If deer carcasses are highly available in the study area, this may explain the high occurrence of deer in carnivore scat and the lack of seasonality in coyote samples. Mice (Peromyscus spp.) were consumed by predators less than expected based on availability, whereas squirrels and chipmunks were consumed by bobcats more than expected. Meadow and red-backed voles were consumed more than expected by both bobcats and coyotes. Mid-sized mammals occurred with expected frequency or lower in predator scats. Coyotes had the lowest diversity and variation in diet, whereas bobcat and bear diets were more diverse including seasonal use of many species. Coyotes exhibited more selectivity (based on changes, and magnitude of changes, in rankings for food item occurrence versus availability) and appear more specialized on deer in all months than bobcats. I analyzed 203 randomly-selected coyote fecal samples using a modified Wisconsin fecal flotation technique. I identified 13 parasite taxa, 9 of which occurred with adequate frequency to permit statistical analysis. No landscape patterns or statistically significant seasonal differences were found in prevalence of parasite taxa, and only A. caninum and Eimeria spp. were significantly higher, and Cystoisospora spp. was somewhat significantly higher, in Bath versus Rockingham Counties. By comparing my data on spatio-temporal patterns of food availability to patterns in the scats of predators, we have better understanding of predator foraging strategies and can identify opportunities for targeted management to balance predator-prey dynamics with human needs and values. More research is needed on the interactions of sympatric predators in specific areas to gain further inferences regarding population-level impacts of predation on deer in western Virginia. / Master of Science

This dissertation explores two themes central to the field of non-equilibrium statistical physics. The first is centered around the use of random walks, first-passage processes, and Brownian motion to model basic stochastic search processes found in biology and ecological systems. The second is centered around clustered networks: how clustering modifies the nature of transition in the appearance of various graph motifs and their use in modeling social networks. In the first part of this dissertation, we start by investigating properties of intermediate crossings of Brownian paths. We develop simple analytical tools to obtain probability distributions of intermediate crossing positions and intermediate crossing times of Brownian paths. We find that the distribution of intermediate crossing times can be unimodal or bimodal. Next, we develop analytical and numerical methods to solve a system of 𝑁 diffusive searchers which are reset to the origin at stochastic or periodic intervals. We obtain the optimal criteria to search for a fixed target in one, two and three dimensions. For these two systems, we also develop efficient ways to simulate Brownian paths, where the simulation kernel makes maximal use of first-passage ideas. Finally we develop a model to understand foraging in a resource-rich environment. Specifically, we investigate the role of greed on the lifetime of a diffusive forager. This lifetime shows non-monotonic dependence on greed in one and two dimensions, and surprisingly, a peak for negative greed in 1d. In the second part of this dissertation, we develop simple models to capture the non-tree-like (clustering) aspects of random networks that arise in the real world. By 'clustered networks', we specifically mean networks where the probability of links between neighbors of a node (i.e., 'friends of friends') is positive. We discuss three simple and related models. We find a series of transitions in the density of graph motifs such as triangles (3-cliques), 4-cliques etc as a function of the clustering probability. We also find that giant 3-cores emerge through first- or second-order, or even mixed transitions in clustered networks.

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Parasites have detrimental effects on an animal's fitness and could play a significant role in shaping the adaptive behaviour of animals. Natural selection may favour those behaviours utilised by animals that minimise the risk and intensity of infections. Animals use a range of behavioural strategies associated with grooming, social, mating, migratory and foraging behaviours to minimise their parasite burdens. Herbivores have two means available for reducing the effects of parasites while foraging. They may avoid parasites or consume plants with anti-parasitic properties. Sheep (Ovis aries) were shown to avoid foraging in areas of the sward contaminated with O. circumcincta infective larvae but could only do so when larvae were associated with faeces. The ability of sheep to avoid contaminated patches of the sward increased as the size of contaminated sward patches increased. This avoidance behaviour resulted in a reduction in the numbers of parasites ingested. Animals infected with O. circumcincta were more selective in their grazing behaviour than uninfected animals with respect to faeces avoidance. In order to determine which plants possess anti-parasitic properties Lotus pedunculatus, Pinus sylvestris, Tanacetum vulgare and Artemisia absinthium extracts were screened against Trichostrongylus colubriformis infections in the Mongolian gerbil (Meriones unguiculatus). Only A. absinthium merited further investigation as it appeared to suppress worm burdens when administered in a high single dose. A. absinthium extracts were subsequently administered to sheep infected with T. colubriformis.

In the analysis of movement patterns of animals, stochastic processes play an important role, providing us with a variety of tools to examine, model and simulate their behaviour. In this thesis we focus on the foraging of specific animals - bumblebees - and analyse experimental data to understand the influence of changes in the bumblebees’ environment on their search flights. Starting with a discussion of main classes of stochastic models useful for the description of foraging animals, we then look at a multitude of environmental factors influencing the dynamics of animals in their search for food. With this background we examine flight data of foraging bumblebees obtained from a laboratory experiment by stochastic analyses. The main point of interest of this analysis is the description, modelling and understanding of the data with respect to the influence of predatory threats on the bumblebee’s foraging search flights. After this detail-oriented view on interactions of bumblebees with food sources and predators in the experimental data, we develop a generalized reorientation model. By extracting the necessary information from the data, we arrive at a generalized correlated random walk foraging model for bumblebee flights, which we discuss and compare to the experimental data via simulations. We finish with a discussion of anomalous fluctuation relations and some results on spectral densities of autocorrelation functions. While this part is not directly related to the analysis of foraging, it concerns a closely related class of stochastic processes described by Langevin equations with non- trivial autocorrelation functions analyse experimental data to understand the influence of changes in the bumblebees’ environment on their search flights. Starting with a discussion of main classes of stochastic models useful for the description of foraging animals, we then look at a multitude of environmental factors influencing the dynamics of animals in their search for food. With this background we examine flight data of foraging bumblebees obtained from a laboratory experiment by stochastic analyses. The main point of interest of this analysis is the description, modelling and understanding of the data with respect to the influence of predatory threats on the bumblebee’s foraging search flights. After this detail-oriented view on interactions of bumblebees with food sources and predators in the experimental data, we develop a generalized reorientation model. By extracting the necessary information from the data, we arrive at a generalized correlated random walk foraging model for bumblebee flights, which we discuss and compare to the experimental data via simulations. We finish with a discussion of anomalous fluctuation relations and some results on spectral densities of autocorrelation functions. While this part is not directly related to the analysis of foraging, it concerns a closely related class of stochastic processes described by Langevin equations with nontrivial autocorrelation functions.

Individual variation in asocial and social behavioural traits can affect patterns of social association. Resultant individual-level variation in sociality can be quantified using social network analysis. Social network analysis has recently been applied to the study of the evolution and development of social behaviour. Though captive systems have provided useful contributions to this endeavour, investigating the factors shaping social structure in wild populations affords superior ecological relevance. The characterisation of the social structure of wild animals has been greatly aided by improvements in automated data collection methods, particularly the miniaturisation of Radio-Frequency Identification (RFID) technology for the purposes of studying the social foraging behaviour of wild birds. In this thesis, I use RFID methods to examine the factors influencing between-individual variation in foraging routines (Chapter Two) and social network position (Chapter Three) in wild populations of a colonial corvid species, the jackdaw (Corvus monedula). I then relate social network position to reproductive success (Chapter Three) and investigate the developmental plasticity of jackdaw social behaviour by determining the effect of early life conditions on social network position (Chapter Four). Finally, I describe the fine-scale temporal dynamics of social foraging, the nature of accompaniment during paired foraging and the foraging benefits of social support (Chapter Five).