Thursday 18 August 2022

Recent Aquatic Warbler records in Cornwall

 Aquatic Warbler is a Red Data species and is one of the rarest and only internationally threatened passerine bird found in Europe. Its population is falling because of habitat loss and drainage of key wetlands.  70% of the world population breeds in the Polesie region of South Belarus. The species breeds in Eastern Europe and winters in West Africa.  In theory this means a westerly passage route via south west England but in recent years, the species has become a major rarity, presumably due to further decline.

Aquatic Warbler, Nanjizal, picture courtesy Reuben Veal.

In Cornwall there are just shy of 250 records since 1951. This seems a lot, but a quick analysis reveals that records have been slim this century. There was a total blank period in Cornwall from 2003 to 2011 and thereafter just seven birds up to 2022, just one being found in the field.

Marazion Marsh is by far the best site with 176 records.  These records accumulated when constant ringing took place here.  Stithians Reservoir has 17 records, 12 of which were found in 1976 (when eight birds were ringed).  Nanjizal had just two records by 2003.  The common theme here is that the species is shy on passage and doesn't give itself up easily. Trapping seems to be the only method where Aquatics are regularly found.

Cornwall records since 2003:

2003: Nanjizal, one trapped 27th Sep.

2011: Marazion Marsh, two juvs trapped 22nd and 23rd Aug.

2012: Gunwalloe, juv trapped 23rd Aug and subsequently re-trapped in Autumn 2013, on migration in France. 

2012: Marazion Marsh, juv trapped 12th Aug.

2015: Lizard, first cal. bird found and photo'd in the field by Tony Blunden, 3rd Oct.

2018: Nanjizal, first cal. trapped, 29th Aug .

2019: Nanjizal, trapped, 7th Sep.

2022: Nanjizal, first cal. trapped, 15th Aug. (6th record for Nanjizal). Retrapped 25th Aug.

Records courtesy CBWPS reports, Derek Julian's and Dave Parker's personal totals and my own records.

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