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Status and conservation of the grass snake in Jersey

Ward, Robert John (2017) Status and conservation of the grass snake in Jersey. Doctor of Philosophy (PhD) thesis, University of Kent,. (KAR id:65819)

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Abstract

Global biodiversity losses are being driven by anthropogenic pressures; the most pervasive of which is habitat loss resulting in fragmentation and population isolation. These issues are prevalent throughout Europe due to high intensity agriculture and increasing human population densities. Limitations imposed by resources and the secretive lifestyles of many species hinder the ability of conservationists to undertake status assessments and identify conservation actions. This thesis investigates the threats to an isolated population of grass snakes Natrix helvetica on the island of Jersey, providing recommendations for conservation management and recovery, whilst testing the suitability of tools for monitoring cryptic species. Grass snakes were historically widespread throughout Jersey; however, anthropogenic influences have restricted their distribution to the west and southwest. Furthermore, recent monitoring efforts have detected few individuals and their status is unknown.

Species distribution modelling indicated similar habitat preferences to radio-tracking and poor suitability of agricultural habitats. Areas close to amphibian prey populations were also suitable whereas those with high road densities were not. A fifth of Jersey contained priority conservation areas, however almost 90% of these areas do not receive statutory protection. Those in the west and southwest should be prioritised for protection due to their proximity to extant subpopulations. Mitochondrial genes identified the population to belong to a western lineage of grass snakes Natrix helvetica helvetica, with a probable natural colonisation prior to separation from northwest France. Within Jersey, microsatellite markers identified three subpopulations, with significant differentiation between snakes in the south and west. This coincides with a dense urban area, through which connectivity needs improvement.

The Jersey grass snake population can be classified as regionally Vulnerable (D2) under IUCN guidelines. The study illustrates how nature reserves are important for maintaining isolated subpopulations and the potential avenues by which statutory protection, sympathetic management practices and efforts to improve inter-reserve connectivity can contribute to conservation objectives.

Item Type: Thesis (Doctor of Philosophy (PhD))
Thesis advisor: Griffiths, Richard
Thesis advisor: Groombridge, Jim
Thesis advisor: Cornish, Nina
Uncontrolled keywords: Channel Islands, conservation genetics, crypsis, insular, Jersey, monitoring, Natrix, occupancy, radio-tracking, snake, species distribution modelling, conservation, biodiversity, grass snake
Divisions: Divisions > Division of Human and Social Sciences > School of Anthropology and Conservation
SWORD Depositor: System Moodle
Depositing User: System Moodle
Date Deposited: 30 Jan 2018 16:10 UTC
Last Modified: 16 Feb 2021 13:52 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/65819 (The current URI for this page, for reference purposes)
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