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Identifying incursion pathways, early detection responses and management actions to prevent grey squirrel range expansion: an island case study in Wales

Lookup NU author(s): Dr Pete Robertson


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Grey squirrels (Sciurus carolinensis) are a non-indigenous species in the United Kingdom (UK) and were eradicated from the island of Anglesey in 2013 through a live-trapping based control programme. In parallel with the eradication effort, native red squirrel (Sciurus vulgaris) population restoration occurred. Red squirrels are a charismatic species, popular with the general public, and consequently people frequently provide supplemental foods for animals on garden bird tables or within squirrel feeding hoppers. The existence of these feeding stations, along with online social media platforms encouraging the reporting of squirrel sightings, resulted in the progressive evolution of a ‘community based’ network for monitoring squirrels. It was anticipated that this level of surveillance would lead to the early detection of grey squirrel incursion onto the island. Incursion contingency plans were drafted in 2008 and annual proactive surveillance trapping was established within woodland near the railway bridge linking Anglesey with the mainland. Against this background, a series of grey squirrel sightings were reported by the public during the autumn of 2015. This information led to the capture of three individuals. However, reporting by the public also included the misidentification of red squirrels as grey squirrels (false positives), unnecessarily increasing trapping efforts and highlighting a confounding factor in landscapes with sympatric squirrel populations. In this Chapter, we critically review the efficiency of reporting mechanisms, responses to sightings and factors affecting interventions. Decisions with regards to the partitioning of resources in response to grey squirrel sightings were influenced by several factors. A targeted response had to balance an array of available sighting evidence, information that often related to geographically discrete areas which, on Anglesey, precluded simultaneous action within separate locations. This ultimately meant that managers had to implement a sequential prioritisation of removal measures.

Publication metadata

Author(s): Shuttleworth CM, Halliwell EC, Robertson PA

Editor(s): Shuttleworth, CM; Lurz,P; Gurnell,J

Publication type: Book Chapter

Publication status: Published

Book Title: The Grey Squirrel - Ecology and Management of an Invasive Species in Europe

Year: 2016

Pages: 475-492

Print publication date: 30/11/2016

Acceptance date: 07/09/2016

Publisher: European Squirrel Initiative

Library holdings: Search Newcastle University Library for this item

ISBN: 9780954757649