Stopped a moment in Kensington Gardens to enjoy a rare patch of sunshine, I hear the squee sound that a dog’s chew toy makes. Ears direct eyes upward. Six parakeets fly around the top of a tall plane tree. Just as I marvel at the beauty — bright green birds, grey tree, blue sky — the birds break formation. Two dive at a branch. A blur of grey fur. Two squirrels race along the slenderest of branches, framed by sky, to the next tree and the next, down to the ground. Where they sneak back to the tree that must have a stash at the heart of its upper branches. The grey squirrels are not a native species; they are pushing out the red squirrels. The parakeets are not a native species; they escaped from an aviary. And I, the foreigner, watch them taunt each other in the heights.