This juvenile American Black Tern was discovered 6 miles NNE of Louth at Covenham Reservoir on September 17th and was still present in early October. Key identification features to note are the dusky flanks, the well defined 'headphone' patches behind the eye and the more uniform upperpart colouring which are all shown well in these superb images by Steve Seal. Despite the aforementioned plumage differences most authorities do not recognise the American form as a distinct species. There are just three previous accepted records for Britain: Somerset 1999; Outer Hebrides 2008; Oxfordshire 2009.
Juvenile American Black Tern at Covenham Reservoir
September 2011. All photos courtesy of Steve Seal