Grey Squirrels, introduced to Ireland in the early 1900s, are now widespread and have impacted the population of native Red Squirrels. They are long believed to descend from a dozen released in Longford in 1911.  Our panel discusses whether later deliberate or accidental introductions also added to their numbers and genetics...

Derek Mooney and guests explore the natural world in all its forms. Listen live every Monday at 10pm on RTÉ Radio 1.