I've not seen a red squirrel in our neighbourhood for a long time now.

The greys are thriving, despite appalling road sense; mainly, because, as many folks have already mentioned, their ingenuity at cracking all those 'squirrel proof' bird feeders.
detirmined squirrel!

When the weaher gets cold here the squirrels just get out their winter wardrobe, dense and much more silvery grey than their summer outfit.