Are pine martens the answer to grey squirrel control?
Journalists seem to think so…..
The Vincent Wildlife Trust Founded in 1975 by Hon. Vincent Weir • • A charity engaged in mammal research, surveys, monitoring & conservation • History of national distribution surveys – otter, water vole, polecat & pine marten • Current focus on rare bats and the smaller mustelids- polecat, stoat, weasel and pine marten.
The pine marten One of six native British mustelids • • Cat-sized, cream bib, bushy tail, prominent pale ears 3-D habitat specialist • • Typically associated with extensive woodland & ‘old growth’ features Prefer to den above ground (tree • cavities) Home range size 1 - 32km 2 • • Omnivorous & opportunistic diet – small mammals, fruit, small birds & invertebrates. Research Education Conservation
The grey squirrel • Non-native. • Introduced to Britain & Ireland. • Threatens survival of native red squirrels through competition & disease (squirrel pox virus). • Cost of grey squirrel damage to commercial forestry in UK = >£10 million per year. • “One of the world’s most invasive alien species” (Lowe et al . 2004). Natural range of grey squirrel in North • America overlaps with American marten and fisher (natural predators) only in very small area (Sheehy & Lawton, 2014).
Pine martens and squirrels in Ireland • Grey squirrels introduced to Ireland in 1911. Grey squirrels present in 26 of 32 • counties (Carey et al . 2007). • In late 1990s, red & grey squirrel populations in some northern counties reported as ‘‘unsettled’’ for first time (O’Teangana et al . 2000). • Anecdotal reports that grey squirrel had declined locally since the 1980s, allowing for a resurgence of the red squirrel population. This coincided with recovery of the • pine marten. • Suggestion that the distribution of the 3 species may be linked (Carey et al . 2007).
Pine martens and squirrels in Ireland • Study carried out in 2011-2012 by Emma Sheehy & Colin Lawton at National University of Ireland. • Investigated the role of the pine marten in grey and red squirrel population dynamics. The majority of respondents (84.7%) wish to see the Pine marten restored in Wales
Pine martens and squirrels in Ireland Methods: Study area: Laois & Offaly (in the midlands) including a buffer zone, & Wicklow (in east). • Sightings and hair tube surveys used to collect distribution data on pine martens & squirrels. Squirrels live trapped to • determine abundance and density. • Squirrel body size, condition & breeding Sheehy & Lawton, 2014 activity recorded. Research Education Conservation
Pine martens and squirrels in Ireland Results: • Strong negative correlation between detection of grey squirrel & pine marten. Only 1 site where both species were found. Grey squirrel population has crashed in 9,000 km 2 of its former • range. Red squirrel has recolonised 6,500 km 2 of its historic range. • • Red squirrel & pine marten populations overlap extensively but grey squirrel & pine marten overlap is limited. • In woodland where pine martens occurred at high density, grey squirrel density was very low & grey squirrel body mass was low & overall health was poor. • High density predator population may be influencing foraging behaviour, body condition, reproductive activity or density in grey squirrel population. Sheehy & Lawton, 2014 Research Education Conservation
Pine martens and squirrels in Ireland Grey squirrel & pine marten distribution & densities from sightings between 2010-2012. Sighting locations (left) & 10km radius kernel density (right). Sheehy & Lawton, 2014 Research Education Conservation
Pine martens and squirrels in Ireland Pine marten diet Grey squirrel % frequency of • occurrence in diet = 15.6%. Similar to contribution of grey squirrel to American marten & fisher diet in North America. • Red squirrel % frequency of occurrence in diet = 2.4%. Consistent with other studies in Ireland & Scotland. Sheehy et al . 2013
Pine martens and squirrels in Scotland • Anecdotal evidence that where pine martens have recovered & expanded their range in parts of Scotland, grey squirrels have declined. • Research underway by Emma Sheehy & Xavier Lambin at Aberdeen University to investigate relationship between pine martens, grey & red squirrels in Scotland.
Pine Marten Recovery Project • Aims to restore viable, self-sustaining pine marten populations across England and Wales where habitat & other conditions are suitable. • First translocations taking place now: 20 animals being translocated from Scotland to mid Wales, to reinforce small existing population.
Feasibility Study • Feasibility study completed in 2014 • Evaluated proposal against IUCN guidelines • Used habitat suitability model to identify suitable release sites • Community/stakeholder engagement in potential release areas • Identify potential conflicts Detailed field surveys & risk assessments • • Disease Risk Analysis completed by wildlife vet & reviewed by veterinary experts
Identifying reinforcement areas • Habitat suitability model (MAXENT) identified areas of suitable habitat for pine marten reinforcement (most suitable areas in green on map) . • Optimal areas will have: - Minimum habitat area and connectivity for viable numbers of pine marten home ranges. - Minimum potential conflict & full support of local communities.
Identifying reinforcement areas Initial release sites in mid- Wales.
Preparing release sites • Gathered baseline data on: • Prey availability (small mammal surveys) • grey squirrel abundance • bat species • woodland structure & composition • Prepared release sites • Release pens • Den boxes
Engaging people Liaising with landowners/users. • • Meetings with NFU/FUW. • 3 public community meetings. • Attendance of local shows (e.g. Welsh Game Fair). • Highlighting local history & heritage – Bele’r coed. • Public opinion survey showed >90% respondents supportive of pine marten recovery.
Sourcing animals • Surveys at ‘donor sites’ in Scotland. • Licence granted by Scottish Natural Heritage to remove pine martens. • Catching 2-4 adults from each site (equal ratio of males & female). Full health check & fitted with radio- collars before translocation. • NRW licences granted to release, and Home Office licences to catch, process & tag animals
Pine Marten Recovery Project Why help pine martens recover? • Native species - it should be here! No evidence of natural recovery in • Wales & England • Intrinsic value, biodiversity, iconic woodland species • Potential for eco-tourism Biological control for grey squirrels? • (Interest in ‘ecosystem services’) • Feasibility study cost £100k • Reinforcement program total >£1m
Pine martens and squirrels in Wales As part of pine marten release, a PhD student is researching direct & indirect influences of pine martens on grey squirrels before, during & after translocation. Research includes: • Pine marten foraging & the extent of predation of squirrels • Squirrel population studies • Radio-tracking of squirrels to investigate behavioural change. • Assessing any reduction in tree damage by grey squirrels over time.
So, are pine martens the answer to grey squirrel control?? Maybe….but that’s not why we’re conserving them! www.vwt.org.uk www.pine-marten-recovery-project.org.uk
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