Black Tern - Autumn

Chlidonias niger

Autumn records spanned from the 8th August to the 11th November, 95 % of them between the 14th August and the 8th October. In some years few were seen, in others larger totals, especially when peak numbers passed in one or two days, as 100 on the 12th September 1981, 98 on the 14th August 1985, 112 on the 27th August 1997, 86 over the two days of the 24th and 25th August 1999, 97 on the 8th October 2001, 536 on the 31st August 2005 with 117 on the 1st September 2005.

The peaks occurred during brief periods of light to brisk southerly winds, particularly from the south east, accompanied by low cloud and mostly with rain or drizzle. On those occasions the terns flew in from out to sea flying directly into the wind. When nearing the shore they mostly turned westwards, which enabled them to continue out to sea but some turned into Cardigan Bay. On the 31st August 2005 groups approaching the land bunched into tight formation and climbed rapidly, almost vertically, to disappear from sight into the low cloud cover. It seems likely they continued on their south east heading, going overland. BWP notes that Black Terns sometimes migrate at considerable height and the beginning of such action was probably witnessed at Strumble Head that day.