With another day of freezing fog, very dangerous on the roads, nature is telling us that, yes, global warming or no, it’s winter. The false acacia, totally leafless, whirs with activity. A big wood pigeon sits impassively, ignoring the small passers-by. Within a few minutes, these include 3 goldfinches, keeping well away from each other in the branches; 2 male blackbirds, similarly, their heads high on the lookout for competitive activity; 4 ring-necked parakeets, never settling for more than a moment, jumping up squawking at the slightest provocation; 2 redwings, handsome with their contrasting eyestripes; 1 fieldfare, markedly bigger, and a handsome bird when seen in crisp winter sunshine rather than today’s murky fog. A few minutes later, a blackcap appeared: still a bird that we think of as a summer visitor, though a few pass through in winter from colder places. Later still, a great tit jumped in and wriggled about; and a little flock of 6 starlings blew in for a few minutes, sadly diminished from the sort of flocks I remember: and even this local flock used to have 7 members.

The effect as birds appear from and vanish into the gloom is rather of one of those popular tales physicists tell to try to make the public feel they understand what nuclear physics is all about: particles and antiparticles are ceaselessly created by the vacuum, and as continuously meet each other and annihilate, returning to their matrix, the apparently endlessly creative fog, which one would otherwise have mistaken for chilly nothingness.