Williamson's Weekly Nature Notes April 1 2009

The Wash has the highest winter population, of 20,000, followed by the Thames Estuary, which has 10,000. Another 10,000 birds use our local harbours from Portsmouth to Pagham, so a grand total of 18,000 cross the county at night bound for the Thames Estuary or Norfolk marshes on the first leg of the journey back to the Russian arctic by mid-May. I have often wondered if they pass close to Gatwick or Heathrow. With news that a gaggle of Canada geese seem to have stopped the engines on the Hudson river crash earlier this year, this may not be idle speculation. However, I remember when I was in the RAF, seeing the radar screens completely swamped with echoes from migrating birds in early April every year, and again in October to such an extent that fighter aircraft were unable to be controlled and were grounded for those few days. Did the Russian Bears which tapped continually on our radar shield at night know the danger the UK was in? It was impossible to see them amongst the so-called anomalous propagation, otherwise known as angels, which millions of robins, mallard, jays, chaffinches, ducks and geese produced on the screens in those days as they hurried across England and the North sea. It was a complete white-out made even worse by the usual high pressure system the birds chose for their journey, which also bent the radar rays, making them follow the earth's curvature. I expect all those problems with the Type 80 radar have been sorted now, even to the echoes from aluminium rings on birds' legs. But bird strikes are still an occasional problem it seems. Once or twice I have been lucky enough to be outside at exactly the moment the brent geese started migration. Once, I heard them skimming the crest of the downs at Kingley Vale. Another time, they were silhouetted wonderfully against the moon at about 9pm right over the top of my home at West Dean. I waited this year but was unlucky. But did anybody hear them go this year? It is a wonderful sound of baying from what were once known as Gabriel's Hounds.