'Identification challenges presented by 2nd winter Kumlien's Gull' by Derek Charles.
In my experience 2nd winter Kumlien's Gulls (Larus glaucoides kumlieni, Brewster 1883) is the rarest age group to be encountered in Ireland. I don't have all the answers to identifying them but I hope this note will at least stimulate debate among birders.
Typical 2nd winter Kumlien's Gulls are usually identified without too much difficulty but there is a gap in our knowledge regarding the degree of variability among some 2nd winter Iceland Gulls (Larus glaucoides) which appear to exhibit varying amounts of wash on their primaries. This problem is not helped by the lack of relevant information coming from the core wintering range of Iceland Gull and until this improves the identification of some birds will be at best problematical.
As with Kumlien's Gulls of all ages the primary pattern is the key to identification of 2nd winter birds. The outer primaries (normally p6 - p10) have a grey/brown wash centered along the outer web of each feather normally heaviest in the centre of the feather and bleeding onto the inner web at the tip. The outer primaries contrast with paler inner primaries. Additional helpful features to look for is a solid grey/brown tail band which is usually present and some individuals show dark eyes. Other subjective features for Kumlien's are slightly larger and heavier bills and shorter primary projections but I don't find these features particularily useful when identifying individuals as there is much overlap between Kumlien's and Iceland Gulls.
To begin, some examples of classic 2nd winter birds. Click on the image for more details.
These examples were all observed in Ireland during the winter of 2007 - 2008. Identification of these examples is not so straightforward. All of these birds may be Kumlien’s Gulls however it is also possible they are well marked Iceland Gulls or perhaps they originate from a Kumlien's / Iceland Gull contact zone and as a result are hybrids. Click on the image for more details.
2nd winter Iceland Gull
Compare these 2nd winter Iceland Gulls alongside classic 2nd winter Kumlien's.
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