Lost and far from home, these whales are emblems for our times | Philip Hoare

From the Thames to the Mediterranean, seeing nature out of place reminds us of our impact on the planet

With the weekend's arrival of a young minke whale stuck in the River Thames - not far from where a seal pup was recently savaged by a dog - it seems marine mammals are appearing everywhere they shouldn't be.

Since the beginning of April, an exotic visitor has been spotted off the coast of southern Europe. A lone grey whale, measuring eight metres long - and 7,000 miles from its fellow Pacific grey whales on the other side of the world - was seen off Rabat, Morocco, at the start of March. It wandered through the strait of Gibraltar - and into an enormous trap, the Mediterranean. Since then its progress has been charted from the north African coast to southern Italy and the south of France, from Naples to the Cote d'Azur. Unable to find its usual source of food, it is growing thinner and weaker in its search for a way out.