Context . As invasive grey squirrels continue to spread, red only areas are becoming rarer. It has been reported that red squirrels can outcompete greys only in pure coniferous woodland. In areas of sympatry with grey squirrels, there are concerns about red squirrels’ dependence on certain coniferous tree species in light of recent tree diseases.

Aims . This study aimed to investigate tree selection by red squirrels in an area vulnerable to the spread of the grey squirrel, but currently free of this species.

Methods . During 2013–14, squirrels were trapped and monitored on a 315-ha managed island, with a woodland characterised by a mixture of deciduous and coniferous species. Radio-tracking revealed that squirrels clustered their activity along a network of yew trees, a preference they showed throughout the year. Trap success was also higher in traps placed on yew trees. Yew and beech were selected most commonly, but squirrels were also observed foraging on other items, such as sycamore flowers and lichen. Squirrels spent 35% of their time foraging, utilising the greatest number of tree species in June (n = 13). In spring, squirrels foraged to a greater extent on the ground than in the trees, and exploited a lower number of tree species.

Conclusions . There has been little previous data on the use of yew trees by red squirrels, but they have previously been listed as a species that is preferred by red squirrels rather than greys. This study has further emphasised the importance of this tree species to red squirrels.

Implications . The continued spread of the grey squirrel may lead to red squirrels becoming restricted to areas of intense management such as parks and, accordingly, optimum tree planting is required from the onset for the long-term maintenance of red squirrels. With recent concern about the disease vulnerability of other coniferous species, this study emphasises the relative importance of yew and other tree species in the distribution of red squirrels.