The recovery of pine marten in Ireland and Britain is reversing native red squirrel replacement by invasive grey squirrels, according to new research presented at the British Ecological Society’s annual meeting in Belfast today (13/12/19)
Researchers at Queens University, Belfast and National Museums Northern Ireland have found red squirrels are responding positively to the increased presence of pine martens across Northern Ireland. So, where pine martens occur, it increases the chances of red squirrels occurring, simultaneously reducing the likelihood of grey squirrels being present.
Historically, persecution of pine marten and loss of their preferred habitat led to severe declines across Ireland and Britain. In Northern Ireland, small, remnant populations were all that remained, but today, the species is recovering, and this comeback may help ensure the long-term future of the red squirrel in Ireland.
Joshua Twining, who will be presenting the research at the conference, commented: “the red squirrels ‘positive response’ is likely due to grey squirrel disappearance rather than red squirrels and pine martens working together.”
Pine martens eat both red and grey squirrels, though the key difference is that red squirrels have evolved alongside pine martens over millennia, making them able to coexist.
Twining said, “The ability of the pine marten to control the grey squirrel and help red squirrel recovery in Ireland and Britain is limited by three things; its ongoing recovery, the lack of forest cover on the island and the presence of urban areas.” Twining and co-authors suggest that grey squirrels will persist in the latter as results show pine marten are forest specialists and avoid urban areas." Although the red squirrel population is increasing in Northern Ireland, the researchers warn that: “unless the issue of control within populated areas is addressed, we risk creating a situation where marten-savvy grey squirrels could recolonise the wider landscape in the future.”
If pine marten are to extend their positive impact on red squirrels, issues impeding pine marten recovery need to be addressed. At present, Ireland and Britain are among the least forested countries in Europe with only 11% and 13% of forest cover respectively. The pine martens’ sphere of influence is limited to its forested havens. Increasing forest cover, would lead to concurrent increases in the pine marten’s ability to control grey squirrels and aid in recovery of the red squirrels.