Recent studies have indicated that avian magnetoreception is based on vision, being both wavelength and luminance sensitive. Using this novel behavioural assay, the ability to respond to changes in magnetic field conditions was tested in the dark and the light. Darkness was found to have an adverse impact on birds' abilities to perceive magnetic field changes. Magnetoreception as measured by reactivity was virtually eliminated in the dark as compared with the same birds' behaviour in normal light conditions.

Using methodology devised by Pearce, Esber, George and Haselgrove (2008), the role of attention in discrimination learning in pigeons was investigated. In Chapter 1 a review of literature revealed several unanswered questions Experiments 1 and 2 explored whether attention is paid to entire dimensions or to individual stimuli. In a test, pigeons learnt a discrimination based upon previously relevant stimuli more rapidly than they did a discrimination based on previously irrelevant stimuli. This was evident when discriminations were based on colours that were close or far apart on the spectrum. Experiment 3 attempted to detect latent inhibition in pigeons. No effect was observed; findings were attributed to the amount of attention paid to a stimulus being determined by the degree of responding to it. In Experiment 4 compounds in which components were superimposed on the other eliminated the effects seen in Experiment 3. Experiment 5 explored whether more attention is paid to reliable or unreliable predictors of outcome. No evidence was found of greater attention paid to partially-reinforced stimuli. Experiment 6 found pigeons learnt more rapidly about previously reinforced stimuli when accompanied by stimuli with low associative strength than with stimuli with high associative strength. Experiment 7 explored whether attention increased to previously non-reinforced stimuli from a discrimination. No evidence was found. Experiment 8 asked the same question but paired previously non-reinforced and previously irrelevant stimuli during Stage 2. The discrimination based upon non-reinforced stimuli was learnt more rapidly than the discrimination based upon irrelevant stimuli. From the findings presented it seems attentional changes were masked by the amount of time a pigeon spent pecking at a stimulus. The exception was the final experiment. It seems attentional changes as envisaged by Mackintosh (1975a) may occur, but are only apparent when the effect of the amount of pecking is reduced.

Scent is thought to be the most important mode of communication for many mammalian species, including otters. Spraint surveys, used widely to monitor otter populations, describe distribution only. Discrimination between identity parameters through chemical analysis of scent marks has been conducted for many species but the feasibility of using this to enhance population monitoring has not been fully tested. Scent presentation experiments were conducted on captive otters and provided some evidence that otters can determine the sex and reproductive status of the scent depositor. These experiments provide the first evidence of a potential role of both volatile and non-volatile compounds in otter communication, and revealed that otters learn where scent signals are likely to be presented. A series of experiments were conducted to optimise methods for the chemical analysis of otter scent. A combination of scent sample collection from otter carcasses and captive otters enabled the description of the chemical nature of otter scent. Scent was associated with age, sex and reproductive status, but not with diet. Scent was associated with individual identity and in females, progesterone concentrations, suggesting a role in reproductive behaviours. Spatial analysis at a national scale revealed differences in scent between genetically distinct subpopulations of otters. On a catchment scale there was no association between scent similarity and spatial proximity. Although scent differed significantly with individual identity, differences were not at sufficient resolution to allow discrimination between unknown samples collected in the wild. This thesis makes several major steps towards unravelling the complexity of otter scent communication and adds to the knowledge of otter biology and behaviour.

ATP dependent chromatin re-modeling factors have previously been shown to play a pivotal role in the regulation of gene expression in several model organisms, including yeast, fruit fly and human. When encountered with a nutrient depleted environment Dictyostelium discoideum enter a process of multicellular development which requires the correct temporal and spatial expression of a large subset of genes. Here it is shown that two of these ATP dependent chromatin re-modelling factors, 1NO80 and CHDC, are required for the correct expression of developmental genes of Dictyostelium discoideum and subsequent multicellular morphogenesis. These factors are identified as having a key role in the earlier stage of aggregation and cellular chemotaxis towards the developmental chemoattractant cAMP. Genetic disruption of genes encoding major subunits of these complexes, arp8 and chdC, both result in a decreased ability to form correct fruiting bodies, also showing a marked decrease in chemotactic ability. In each case, these defects are seen to occur through different mechanisms, indicating the role of multiple pathways in the regulation of Dictyostelium chemotaxis. Interestingly, both mutant cell lines are also responsive to the neuropsychiatric treatment drug lithium and are shown to affect elements of the inositol signaling pathway.

Consistent personality differences (e.g. shyness, sociability) among animals have been frequently reported by scientists. Such information used to be considered unscientific, even though it was widely used to describe animals and predict their behaviour (Hebb, 1946). Over the past three decades however animal personality has been studied systematically in various species (Gosling, 2001), using provided lists of descriptors, consistent with the five-factor model of personality (Costa & McCrea, 1992). Few researchers have allowed raters to produce their own list of descriptors (Dutton et al., 1997; Wemelsfelder et al., 2000), and none have investigated the potential influence of human individual differences on ratings. The three main goals of this thesis were (i) to develop in-depth personality profiles of domesticated horses, (ii) to investigate the effect of personal backgrounds and attitudes of observers in their construction of these profiles, and (iii) to provide insight into the reliability and validity of the provided assessments of horse personality. The thesis starts with a literature review of personality psychology, psychometrics, animal and horse personality; followed by the introduction of the concept of animal-as-a-scientist. As methodology is an important part of the project, the repertory grid technique (RGT) originally developed by Kelly (1955), was employed as a novel method to assess horse personality. This method gives observers the freedom to generate their own descriptors, which allows them to integrate the totality of their experience with animals into personality constructs which are meaningful to them. RGT has previously been used for personality assessment in chimpanzees (Dutton et al., 1997) and for the assessment of individual styles of interaction in pigs (Grajfoner et al., 2002). The experimental part of the thesis consists of two studies. In both, horse personality was assessed by groups of human participants, either familiar or unfamiliar with the horses. The familiar groups assessed the horses based on their past experiences. The unfamiliar groups watched short videos of horses interacting with a human. In the first study 44 female observers rated 21 horses from two stables. The results show a significant degree of agreement within the observer groups for 95% of horses. However, correlation of horse personality scores between the observer groups was not significant. The degree of agreement was higher when the observers were familiar not only with the horses but also with the descriptors (Adams-Weber, 1970). In the second study we further investigated the observed incongruity between familiar and unfamiliar observers. A novel object test was added to provide the unfamiliar observers with more information about the horses. Thirty four female observers rated 38 horses from three stables. Again, the degree of agreement was highly significant within the observer groups; however, correlation of the results between familiar and unfamiliar observers was only marginally improved. The degree of agreement was not consistently higher when the horses were rated on elicited constructs. Both studies showed that two personality dimensions, neuroticism and extroversion, are fairly robust in horses. The third dimension, agreeableness, was generated only by familiar observers. Contrary to expectations, observers’ personality, empathy or emotional intelligence did not significantly affect the degree of agreement or how they rated the horses’ personalities. Assessment of individual differences in horses using qualitative descriptors generated by the observers themselves is therefore not observers’ self projection. These results make a significant contribution to the debate on anthropomorphism. The overall degrees of agreement between the observers indicates consistent reliability of the RGT throughout the observer groups in both studies. Finally, the academic and practical implications of the study are discussed. On an academic level, individual differences in animals are of pivotal importance for understanding personality in the contexts of evolutionary, comparative and social psychology. On a practical level horses are, according to their individual differences, selectively used for different purposes: horse assisted therapy, racing and the police. Avenues for investigating the relationships between animal personality, performance and welfare should therefore be further explored.

This project provided an exceptional opportunity to describe diving behaviour, movements and to characterise critical habitats of blue sharks in the North-eastern Atlantic using satellite and archival telemetry.  Tracked blue sharks displayed southward movements away from the tagging areas, exhibiting pronounced site fidelity to localised high-productivity frontal regions.  Blue sharks also displayed a high degree of variability in vertical movements. Shifts in diving behaviour were detected both within and between individuals, whereas behavioural phases were linked to the thermal structure of the water column in coastal areas, and to changes in prey distribution or type in offshore regions.  High resolution data showed that blue sharks shift between Brownian (in productive habitats) and Lévy (less productive waters) behaviours.  Vertical movements ranged from the surface to 1160 m, and water temperatures varied between 7.2-27.2°C.  Behavioural data was also crucial in determining the degree of spatial and temporal overlap, and thus vulnerability, between blue sharks and high-seas longliners.  Confirmed fishing mortality was ~11% with four tagged sharks caught by surface longliners.  Simulations showed that boats/sharks overlap was higher in winter and early spring, with the majority of simulated sharks (~88%) at risk at least one day year-1.  Our results indicate that, depending on which geographical regions are occupied at specific times, different segments of the blue shark population face differential risk from longlines.  Sequencing of mitochondrial DNA suggested an absence of spatial genetic differentiation throughout the North Atlantic, providing strong evidence that blue sharks comprise a single population in this region.

In seeking new hosts, entomopathogenic nematode foraging strategies are believed to range from sit-and-wait foragers (ambushers) to widely active foragers (cruisers).  This study investigated the behaviour, dispersal and competitive ability of entomopathogenic nematodes of the genera <i>Heterorhabditis </i>and <i>Steinernema </i>in relation to soil habitat. The host finding and competitive ability of <i>Steinernema carpocapsae, </i>an “ambusher” and <i>Heterorhabditis megidis, </i>a “cruiser” in two contrasting soil habitats (sand and peat) showed “habitat-specific” differences in foraging mode between the two species.  In peat, <i>S. carpocapsae </i>outcompeted <i>H. megidis </i>in terms of host finding, whereas the opposite was true in sand.  In the appropriate habitat, both nematodes showed behaviours not predicted by their supposed foraging strategy.  Experiments examining the interspecific interactions between <i>S. carpocapsae </i>and <i>H. megidis </i>also showed significant differences in the population dynamics between the two species in relation to habitat. Nictation behaviour is frequently cited as a host finding strategy in ambush foraging nematodes. The study confirms that ambush foraging species <i>S. carpocapsae </i>and <i>Steinernema scapterisci </i>frequently nictate, but show that habitat is an important factor regulating this behaviour.  This study also demonstrates the ability of the cruise foraging nematode, <i>H. megidis </i>to nictate on habitats not previously examined.

In this study, spatial and temporal variation in fat content and temporal variation in maturation of North Sea herring were examined. Fulton’s K, a widely used condition index, was proven to be an inconsistent measure of individual herring fat content, whereas relative condition factor is a more accurate measure.  The Distell fish fatmeter was shown to be an accurate measure of individual herring muscle fat content and was used throughout the study. Individual herring biological and fat data were collected during the annual acoustic North Sea herring survey in 2006 – 2007. Analyses of these data showed that immature herring in the northern North Sea were larger and had higher fat contents than those in the south, in 2006.  This spatial gradient may be due to spatial variability in temperature and food abundance. Individual-level analyses using three years of field data demonstrated that North Sea herring must reach a length threshold of approximately 250 mm before the onset of maturation can occur.  However, stock-level analyses using data provided by the ICES herring stock assessment, indicated that maturation of North Sea herring is not affected by density-dependent factors or by mean North Sea surface temperatures.  This study demonstrates that the accuracy of different measures of condition should be tested before being used in research and that spatial and temporal variability in fat content should be considered when conducting studies on fish condition and other life history parameters.

Feeding behaviour of trained rainbow trout was investigated by the use of demand feeders, under different light conditions. The effects of the energy content of diet, and the size, colour and texture of feed pellets, on the feeding behaviour, were studied. An attempt was made to locate the assumed centres for feeding and satiety in the hypothalamus of brain by the intraperitoneal injections of goldthioglucose. Feeding under nine different constant photoperiods at 160 lux, at a temperature of 13.5°C, showed that trout exhibit a rhythmic pattern of feeding behaviour in all photoperiods except in continuous darkness. Feeding rhythms of trout attributable to the degree of gut distension were formed every eight to ten hours. Further studies by varying levels of light intensity revealed the interaction of light intensity and photoperiod. At shorter photoperiods lower levels of light intensity decreased the feeding activity in terms of food intake but by increasing the photoperiod the same feeding activity was accomplished as by the fish subject to a short photoperiod but under higher light intensity. Simulated effect of increasing and decreasing daylengths did not affect the overall food intake and growth performance. Trout are quite efficient in adjusting their food intake in terms of energy content. Colour, size and texture of feed pellets affect the feeding responses and elicit preferential food selection behaviour in trout. Goldthioglucose induced some reversable toxic effects upon general physiology of trout and did not produce any lesions in the assumed areas of feeding and satiety centres in the brain. It was concluded that the feeding behaviour of trout exhibited selective preferences according to the physical nature of food items and those preferences could be further influenced by the biotic and abiotic factors, light being one of the most important abiotic factors.

No description available.