My fellow blogger nahrvalur tells us that in a forest park in County Down, the native red squirrel (Sciurus vulgaris) is recovering from a population crash associated with squirrel pox.
Since the North American grey squirrel (Sciurus carolinensis) was introduced here in the late 19th century, its populations have soared while the red squirrel has become rare. Is that because of the squirrel pox? Maybe so. Squirrel pox kills the red squirrel whereas the grey squirrel can carry it without harm. So the greys may have infected the reds, causing the reds’ population crash. It’s a classic story of an invasive species bringing in an infectious agent.
But I’ve also heard other hypotheses. Some people say that the greys outcompete the reds. I’ve heard it said that the two squirrel species prefer different kinds of woodland. Conifers for the red, broadleaved trees for the grey. Whatever the reason, it’s good to know that the reds are coming back in Co Down.