Grey squirrels are predated significantly more than red squirrels, with pine martens targeting greys exclusively in spring and summer, during their breeding season
New research by Queen’s University Belfast shows that native European pine martens (Martes martes) predate on non-native grey squirrels (Sciurus carolinensis) significantly more than red squirrels (Sciurus vulgaris).
The findings, published in Mammalian Biology earlier this year and funded by UK wildlife charity People’s Trust for Endangered Species (PTES), also show that although both squirrel species are on the pine martens’ menu, pine martens predate on grey squirrels exclusively in spring and summer, during the squirrels’ breeding season.
As such, it’s now thought pine martens may raid grey squirrel nests (known as ‘dreys’), specifically targeting juveniles and females caring for young. This provides a plausible mechanism for the decline in grey squirrels seen across Ireland and Britain.
A native pine marten. Credit Dr. Joshua P. Twining.
The research, led by Dr. Joshua Twining from the School of Biological Sciences at Queen’s University Belfast, also showed that pine martens do predate on native red squirrels, but at a much lower level. Red squirrels have adapted to live alongside pine martens in the evolutionary landscapes of Europe, thus, red squirrels appear to have a greater awareness of the threat posed by pine martens. Grey squirrels may also be energetically more valuable, and therefore preferable to predators like pine martens as they are larger and are found in higher numbers than red squirrels.
Dr. Joshua P. Twining, from the School of Biological Sciences at Queen’s University Belfast, adds: “Our findings align with the evolutionary physiology and morphology of many small carnivores – slim and slender, pine martens are adapted to pursue prey into small ‘hidey holes’, such as dreys, that other predators cannot access. With semi-retractable claws, and extremely flexible joints which can turn almost 180 degrees, pine martens have evolved to climb. Although such adaptations make pine martens less efficient at chasing down prey, being the only arboreal predator in Great Britain and Ireland gives them easy access to the refuges of squirrels high up in trees.
Our results are interesting as they help explain the mechanism underpinning how pine martens are able to regulate invasive grey squirrel populations, and give a much-needed boost for another one of its prey species, our native red squirrels.”
This magnificent yet mysterious member of the mustelid family is native to Britain and was once one of the most abundant predators in the country. Now, after centuries of widespread persecution and habitat loss, most recent estimates suggest there are only around 3,000 in Ireland and 9,000 in Great Britain, with only approximately 100 thought to be living in England. Just last week, pine martens were listed as ‘Critically Endangered’ on the Red List for England’s mammals.
Nida Al-Fulaij, Grants Manager at PTES, says: “Results like Joshua’s are a ray of hope for this beautiful species, as not only are pine martens naturally helping to reduce numbers of non-native, introduced species such as grey squirrels (one of the main threats to our native red squirrels), but also as their numbers are finally starting to recover in parts of Britain and Ireland too.
It’s important that we understand exactly how pine martens are faring, which includes their predation habits. Pine martens are desperately in need of our help, but this is very positive step forward in our understanding of this species, which ultimately will help us to conserve them long term.”
Over the last 40 years PTES has awarded £7.5 million to conservation research, supporting over 200 species in more than 60 countries and funding 102 internships since 2002. The charity’s intern alumni include conservationists working for universities (such as Joshua), wildlife NGOs and ecological consultancies. The work of previous PTES funded interns includes work on DNA extraction and identification to help stop the trade in endangered wildlife – a subject that is now more pertinent than ever.
The paper, entitled “The dynamics of pine marten predation on red and grey squirrels”, can be accessed here. To find out more about this project, click here, and to find out more about PTES’ internships visit here.
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For interview requests, high res images or more information, please contact Adela Cragg:
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Notes to Editors
Available for interview:
Dr. Joshua P. Twining, Lead-author, School of Biological Sciences, Queen’s University Belfast
About PTES
• PTES, a UK conservation charity created in 1977, is ensuring a future for endangered species throughout the world. We protect some of our most threatened wildlife species and habitats, and provide practical conservation support through research, grant-aid, educational programmes, wildlife surveys, publications and public events.
• PTES’ current priority species and habitats include hazel dormice, hedgehogs, water voles, noble chafers, stag beetles, traditional orchards, native woodlands, wood pasture and parkland and hedgerows.
• PTES has Species Champions for three of its priority species: for hedgehogs The Rt Hon Chris Grayling, MP for Epsom & Ewell, for water voles The Rt Hon Hilary Benn, MP for Leeds Central and Chair of the Brexit Select Committee, and for dormice The Rt Hon Matt Hancock, MP for West Suffolk and Secretary of State for Health and Social Care.
• Visit www.ptes.org and follow PTES on Facebook, Twitter, Instagram, YouTube & LinkedIn.
About Queen’s University Belfast
• Queen’s University Belfast is a member of the Russell Group of the UK’s leading research-intensive universities. Queen’s is ranked 173 in the world (QS World University Rankings 2020) and is a UK top ten research-intensive university (REF 2014/ Times Higher Education). Founded by Queen Victoria in 1845, as one of three Queen’s Colleges in Ireland, it became an independent university in its own right in 1908 and, today, combines its international academic reputation with its standing as a leader in innovation and education. The University has won six Queen’s Anniversary Prizes for Further and Higher Education, five Times Higher Education Awards, and is currently the leading institution in the UK for the commercialisation of its intellectual property and for knowledge transfer partnerships. Four Global Research Institutes are the University’s flagships for interdisciplinary research in areas of major societal challenge, including inclusive secure and enriched societies, technology futures and a healthy global population.
• For more information, please visit www.qub.ac.uk or follow us on Twitter @QUBelfast