Upon reading a passage in ‘Weather and Bird Behaviour’ by Norman Elkins I was reminded of this Autumns arrival of Nearctic birds into the UK after that hot Indian summer we all endured. The passage referred to the summer of 1976 and the Nearctic vagrants that occurred in the following Autumn.
“One of the most notable autumns for (Nearctic) vagrancy was that of 1976, when 25 individuals were recorded. Over 60% of these were Northern species displaced while on normal Southward migration over the sea – Grey cheeked Thrush, Yellow-rumped Warbler and Blackpoll Warbler. This large, unprecedented fall (there were 14 of the last-mentioned species, of which most appeared in multiple arrivals in the first nine days of October) was attributable to the abnormal atmospheric circulation. A proximate cause of the long British drought which ended in September of that year was the extreme northern position of the polar front jet stream. The jet suddenly shifted south from this position in September, and, in combination with other factors resulting from the long hot summer, this produced unusually vigorous cyclonic activity which was ideally suited in transatlantic vagrancy in October.” P159
A touch of ‘déjà vu’ perhaps?
One American bird we encountered this year on Scilly, earlier this month, was an American Buff bellied Pipit. Always elusive in long grass and bad light it was just one of the cast of transatlantic vagrancy that has defined this Autumn.
Letter From Norfolk 