Four red squirrels have been successfully reintroduced to Castle Ward estate to help the threatened mammals make a comeback in Northern Ireland.The species has faced huge declines in the UK and Ireland due to the spread of the invasive grey squirrel from North America and the loss of habitat. However, they are slowly starting to recover thanks to conservation efforts.Ulster Wildlife say Castle Ward's woodland offers the perfect location for reds to flourish as it is free from grey squirrels, thanks to a healthy pine marten population which provides natural control, alongside help from local volunteers.