Squirrels away with the birds

I SAW a squirrel the other day. It ran across the road in front of my car. It was quite a narrow road with Scots pine trees on either side and it was a red squirrel.

On the face of it this isn’t a very dramatic thing to report. But it is actually an example of one of the most interesting developments in European mammal ecology for decades.

In Ireland, Britain and Italy, red squirrel numbers declined for nearly a century while populations of the larger North American grey squirrel increased and spread. Exactly how the grey squirrels ousted the reds is debated by biologists but there is no question that it did occur practically everywhere they came into contact. There were fears that the red squirrel might even become extinct.

Then, in the early years of this century in the Irish midlands, reports began of a sudden reversal of the trend. Greys started to disappear and reds to reappear. I live in the midlands, in north west Kildare, and I have seen this change unfold in precisely the way that the scientific papers describe. Thirty years ago reds and greys seemed to exist in roughly equal numbers in the woods in the area — slightly more reds in the coniferous forestry and slightly more greys in the broad-leaf woodlands. Then there was a dramatic increase in the grey squirrel population and the reds disappeared.

About five years ago the greys suddenly disappeared. It took a little while for the reds to make a comeback but it does seem to be happening. Apart from the one I spotted from my car, a neighbour has a red visiting a bird feeder and I have had three or four other local sightings reported to me.

But perhaps the most interesting piece of anecdotal observation came from another neighbour who has a small wood, mainly beech and oak, on his land. For decades he had been plagued by grey squirrels damaging his trees and robbing his vegetable garden. Two years ago they disappeared over the course of a couple of months, along with the rabbits that were also bothering him. And twice he spotted pine martens on his land.

The theory is that pine martens are spreading in the midlands, where they’ve been largely absent for about a century, and that they prey selectively on greys rather than reds. There may also be an indirect effect, which is a bit complex but boils down to the fact that the very presence of pine martens scares the bejaysus out of greys and they leave the area.

I have one small doubt. At the same time that pine martens arrived here from the west buzzards arrived from the east, and they’re equally fond of a meal of grey squirrel.