The interaction of Sika deer (Cervus nippon Temminck 1838) with lowland heath mosaics.

Abstract

Sika deer (Cervus nippon) has become an invasive species in many parts of the world. In the south of England large populations appear to be concentrated in landscapes comprising of mosaics of lowland heath, woodlands and grassland. Despite the association between the distribution of Sika deer and that of lowland heath, little is known regarding the extent to which Sika deer utilize lowland heath and their impacts on its plant and animal communities. The aim of this thesis was to investigate the ecological interaction of Sika deer with lowland heath set in a mosaic of other habitats. Specifically, the main three objectives of this thesis were: i) to investigate the different ecological factors affecting the distribution and habitat use by Sika deer; iii) to explore consistency in Sika deer habitat associations as a potential tool to predict the distribution and abundance ofSika deer; iii) to investigate the ecological impacts of the usage of areas of lowland heath by Sika deer upon plant and animal communities oflowland heath. Results showed that Sika deer distribution and habitat use are affected by the availability of habitats, landscape structure and human disturbance at both the landscape and home range scale (i.e. few hundred of hectares and few dozens of hectares respectively). At the landscape scale, Sika deer seemed to use the requirement for safe access to pastures as the main criteria for their habitat selection. At the home range scale, the criteria of choice in the use of resources by Sika deer seemed to be related to a requirement for an appropriate balance of food and cover as the selection of pastures and cover were inversely related to their availability. However, human disturbance, as a form of perceived risk, was also a limiting factor of habitat use at the home range scale. Consistencies in the habitat selection by Sika deer at the landscape scale between areas with similar landscape were detected, which could potentially be used to develop models to predict the distribution and abundance of Sika deer and their subsequent impacts in areas of lowland heath. This study has found a different response of plant and animal communities between dry and wet heath to levels in usage of areas of heath by Sika deer. The existence of a threshold in the local density of Sika deer on areas of heath above which dry lowland heath showed signs of decline in quality has also been identified.