Aline Denton has asked me if it's true that the number of Purple Sandpipers overwintering in Aber has been dropping over the last few years, and if so, do we know why?
The short answer to the first part is yes. Numbers peaked in the late 1980's - early 1990's, with max counts of 21 in 1988, 24 in '89, 25 in '90 (highest count), then between 20 and 22 in subsequent years until 21 in 1995.
Then there was a gradual decline.from 17 in '97 to 14 in 2000, 12 in '05, then a rally with 20 in '09, 17 in '11 and 15 in '12 and '15. Since 2016 max counts of 10 in '17 and '18 and 8 in 2019, the last year for which I have figures.
As to why: it could be cyclical. The Birds of Cardiganshire, 1966, says that since it was first recorded in 1927 there are usually 5 - 10 birds present, and Birds of Ceredigion, 2010, shows maxima of 5 - 15 from '68 to '87, with single figure counts in about half of those years.
Of course, there may well be other reasons, but I've taken up enough space already.