This thesis explores the use of tropical butterflies as indicators of forest disturbance, fragmentation and forest recovery. The disturbance level of habitats was found to be characterised by the rate of the fraction of species accumulated, with species in undisturbed habitats accumulating more slowly. Undisturbed habitats, but not more disturbed ones, were found to have a vertically stratified butterfly assemblage between the forest understorey and canopy, and certain species were found to be horizontally stratified from the forest edge. No significant effect of breaks in a forest habitat to the dispersal of certain fruit-feeding butterflies was found, but for species which did not cross breaks, it was not possible to determine whether this was due to low numbers of captures or because breaks acted as barriers to dispersal. <i>Cissia arnaea</i> (Nymphalidae: Satyrinae) was present in significantly greatest abundance in 30 year selectively logged forest, even though canopy openness was not significantly different from that found in 5 year forest. Conversely, <i>Colobura dirce</i> (Nymphalidae: Nymphalinae) was found in greatest abundance in the O and 5 year forest and least abundant in the 30 year forest. It is possible that these species could be used to indicate forest recovery following selective logging. Population size estimates and average residency rates were calculated for <i>Cissia penelop</i>e and <i>Morpho peleides</i> from fruit trap data. Community structure in the <i>Cissia</i> genus was explored, and the relationship between local abundance and geographic range size investigated and certain restricted range species were not found to be adversely affected by forest disturbance in Trinidad as expected (Thomas 1991 and Hamer et al. 1997).

No description available.

No description available.

Studies have established that birds are affected by logging and largely adversely. However, which species are affected, and to what degree, remains unanswered. In particular there is a need to establish why birds decline. Studies show insectivores to be the most vulnerable, but factors affecting insectivorous bird survival are unknown. The purpose of this study is to confirm which species are vulnerable, and the reason why. This study demonstrates the high proportion of understorey bird species which are affected by logging and the large extent by which most species are adversely affected. Not only did the majority (about 80%) decline, but two-thirds of species were severely affected (declined by 50% or more), and a third exhibited acute decline (of over 75%). Only generalists and nectivores are not adversely affected by logging. The abundance of understorey invertebrates also declines following logging. Howwever, pertinent to insectivorous birds, this decline is more significant for the prey groups. It is dependent on substrate, and becomes more severe in drought. For this reason temporal changes in prey availability are likely to be as important as determinants of local bird densities as mean prey availability in logged forest. The lower range of prey availability is likely to be a critical factor in bird persistence in logged forest. Results indicate that drought is the mechanism through which habitat disturbance causes a decline in prey abundance. This decline in arthropods appears to directly impact on insectivorous birds such as babblers. Arthropods (at least those that are bird prey) and babblers are associated with microhabitats that are uncommon in logged forest. The response of three arthropod communities (foliage, ground and suspended litter) to disturbance depends upon how the logged microhabitats available approximate the natural microhabitats they prefer. Skids and gaps are avoided, and arthropod abundance depends directly upon the availability of preferred and usable microhabitats. Such microhabitat becomes increasingly rare with increased severity of disturbance. Insectivorous birds decline because optimium foraging sites are rarely available, and they experience a decline in prey availability. The decline in density of babblers is due at least in part to prey scarcity. The foraging success of babblers declines in logged forest, on average by 80%. Logged attack rates are universally lower (for all 15 species) than those of undisturbed forest. Arboreal, low level and terrestrial babblers all have a lower attack yield in logged forest, which suggests that babblers consume less prey in logged forest than in primary forest. Foraging preferences also explain the relative decline of babblers. The foraging strategy of babblers dictates how vulnerable they will be to logging, and it is clear that it is specialisation specifically that causes species decline. This graduated response to logging can also be predicted on the basis of microhabitat use, and is also explained by the magnitude of disturbance. Understorey birds show greatest decline in abundance where the degree of disturbance is most severe. This implies that forest management could greatly affect bird survival.

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No description available.

The phenomenon of bat mortality at wind turbine installations has been generating increasing concern, both for the continued development of the wind industry and for local ecology. Bat-turbine interactions appear to be globally widespread, but are not well understood. The work outlined in this thesis primarily addresses the acoustic properties of moving turbine blades and the way in which bat-like pulses interact with them. In addition, possible factors for bat attraction to wind turbine installations are assessed. The main contributions of this thesis are (1) the formulation and application of a novel equation to rate turbine rotors in terms of bat detectability, identifying that features such as rotor angular velocity, number of blades, blade width and bat species all influence the likelihood of rotor detection; (2) passive and active ultrasonic measurements from turbine rotors in order to assess the nature of acoustic bat interaction with turning blades, showing that frequency and amplitude information in returned echoes can vary significantly, echoes may be attractive to bats as mimicry of echoes returned from flying insects, and that some turbines do not emit ultrasonic noise detectable to all bat species; (3) assessment of the Doppler shift profiles generated by moving blades in order to investigate the changing nature of frequency information returned to an echolocating bat, concluding that blades turning under low wind speed conditions may not be detectable by some bat species; (4) Monte Carlo simulation of bat-like rotor sampling to account for the temporally short nature of reflected echoes, with the result that some bat species may not be able to achieve enough echoes to accurately interpret blade movement in the short approach time-window; (5) the creation and utilisation of artificial bat-like pulses for lab-based experimental work and (6) the investigation of insect attraction to turbine paint colours to determine the potential abundance of bat prey around turbine installations, finding that existing turbine colours are significantly attractive to insect species. By applying the conclusions of this work suggestions for the mitigation of the problem are detailed, the implementation of which may help to reduce the issue of bat mortality for both the wind industry and bat species in the future.

This thesis describes a study on the foraging ecology of the wood ant Formica rufa Linnaeus (Hymenoptera: Formicidae) at Burnham Beeches, Buckinghamshire over the period January 1994 to June 1996. Detailed observations were made on the foraging behaviour during this period and the food supply of two colonies was experimentally altered by food supplementation and food denial through grease-banding of trees within a 50 m by 50 m area centred on the nest. The foraging areas of F. rufa colonies were determined by observing trails to trees and showed seasonal variation. The size of the foraging areas, their tree composition, the mean distance travelled by foragers and the extent to which particular trees were repeatedly foraged were monitored. There was stability in foraging areas between years due to colony persistence. Food supplementation did not alter the foraging area of the nest. There was some evidence that the extra resources were channelled into producing more sexuals. Food denial caused the denied nest to expand its foraging area. The amount of honeydew collected by F. rufa was experimentally determined. The amount of prey taken was estimated from a survey of the literature. The proportion of net primary productivity moved by a F. rufa colony across its foraging area was estimated as 0.12 % to 0.47 %. The effects of the distribution of F. rufa on other ground living invertebrates was experimentally investigated. The presence of F. rufa was found to be significantly negatively correlated with the presence of predatory Coleoptera and significantly positively correlated with the presence of the myrmecophilous staphylinid beetle Zyras humeralis (Gravenhorst). The monitoring of the foraging areas and determination of the relationship between the presence of F. rufa and other ecological groupings allows this work to be used to inform the ETM framework, a proposal for spatially delineating ecosystems.

No description available.

No description available.