Invading and expanding : range dynamics and ecological consequences of the Greater White-Toothed Shrew (Crocidura russula) invasion in Ireland

McDevitt, A; Tosh, DG; Montgomery, WI; Lusby, J; Reid, N; White, TA; McDevitt, CD; O'Halloran, J; Searle, JB; Yearsley, JM

Abstract

Establishing how invasive species impact upon pre-existing species is a fundamental question in ecology and conservation
biology. The greater white-toothed shrew (Crocidura russula) is an invasive species in Ireland that was first recorded in 2007
and which, according to initial data, may be limiting the abundance/distribution of the pygmy shrew (Sorex minutus),
previously Ireland’s only shrew species. Because of these concerns, we undertook an intensive live-trapping survey (and
used other data from live-trapping, sightings and bird of prey pellets/nest inspections collected between 2006 and 2013) to
model the distribution and expansion of C. russula in Ireland and its impacts on Ireland’s small mammal community. The
main distribution range of C. russula was found to be approximately 7,600 km2 in 2013, with established outlier populations
suggesting that the species is dispersing with human assistance within the island. The species is expanding rapidly for a
small mammal, with a radial expansion rate of 5.5 km/yr overall (2008–2013), and independent estimates from live-trapping
in 2012–2013 showing rates of 2.4–14.1 km/yr, 0.5–7.1 km/yr and 0–5.6 km/yr depending on the landscape features
present. S. minutus is negatively associated with C. russula. S. minutus is completely absent at sites where C. russula is
established and is only present at sites at the edge of and beyond the invasion range of C. russula. The speed of this invasion
and the homogenous nature of the Irish landscape may mean that S. minutus has not had sufficient time to adapt to the
sudden appearance of C. russula. This may mean the continued decline/disappearance of S. minutus as C. russula spreads
throughout the island.

• Journal Article Type: Article
• Acceptance Date: May 27, 2014
• Publication Date: Jun 23, 2014
• Deposit Date: Jan 25, 2016
• Publicly Available Date: Apr 5, 2016
• Journal: PLoS ONE
• Electronic ISSN: 1932-6203
• Publisher: Public Library of Science
• Volume: 9
• Issue: 6
• Pages: e100403
• DOI: https://doi.org/10.1371/journal.pone.0100403
• Publisher URL: http://dx.doi.org/10.1371/journal.pone.0100403
• Related Public URLs: http://www.plosone.org/
• Additional Information: Funders : Irish Research Council;Heritage Council Ireland;Genetics Society;Vincent Wildlife Trust