Recovering pine marten benefits red squirrels, but the grey squirrel still persists in urban areas - Queen’s University Belfast

Research led by Queen’s has found that whilst red squirrels are responding positively to the increased presence of the pine marten in Ireland and Britain, its ability to control grey squirrel is limited by lack of forest and presence of urban refugia.

The research, carried out in partnership with National Museums Northern Ireland, has been published today (Monday 15 June) in Journal of Applied Ecology.

It found that despite the on-going recovery of the pine marten, and its ability to provide natural biological control of the invasive grey squirrel, isolated populations of grey squirrels in parklands in towns and cities are still likely to persist.

The study used data from 332 sites across Northern Ireland covering all sizes and shapes of woodlands in both urban and non-urban areas. To collect the data, a team of 70 citizen scientists deployed a camera trap at sites at randomly selected locations. The researchers used data to measure the co-occurrence of the species throughout the region. Models were then used to produce predictions of the future distribution of the three species. The probability of occurrence for each species was estimated in every 1km2 in Northern Ireland based on interactions between habitat suitability and the presence of other species.

The results predict that grey squirrels will still persist in parkland areas of towns and cities as pine martens were shown to be forest specialists and displayed strong avoidance of human settlement and disturbance in and around urban areas.

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