Yesterday a small but significant event took place outside my window. First two and then a small colony of housemartins gathered on the nearby telegraph wire. (It was only possible to photograph a sample section.) It was a clear indication that the seasonal migration is about to begin. During the next week or so these small birds will leave and fly south to Africa – quite probably to South Africa or Namibia – and will return in April or early May. Many will find their way back to the same location, but not necessarily to the same nest.