Yellow-legged Gull? - Kalmus Beach - April 14
Home

MA Bird Pictures

2011 Pictures

April Pictures

Click on any picture for a larger image or a page with more pictures
This very interesting gull found by Keelin Miller on April 9 is widely reported as a Yellow-legged Gull (Larus michahellis) and has most likely been added to many a life list in the state.

Several features do indeed support that ID:
  • Back color being a shade of gray that's in between Herring and Lesser Black-backed Gulls.
  • Bright yellow-orange legs
  • Red orbital ring
  • Extensive black in the primaries
If indeed it is a Yellow-legged Gull - then which subspecies (or race)?

In Newfoundland they regularly identify overwintering Yellow-legged Gulls (see Dave Brown's excellent blog). So far, the ones (tentatively at least) identified to subspecies have all been 'atlantis', and it would make sense that any YLGU's making it to Massachusetts likely would be that variety as well.

That the Hyannis bird appeared smaller and slightly shorter legged fits in well with it being an atlantis - the smallest YLGU subspecies. The nominate michahelllis is usually larger and has longer legs; but separating them is by no means an easy task - especially in full alternate (summer/breeding) plumage.

Looking at the pictures of the Hyannis birds, several features pops up as being "not quite right" for a YLGU:
  • Head shape - seems rounded to me. YLGU are supposed to have "angular heads" with sloping forehead and a flat crown.
  • Bill: Dave Brown mentions in his blog that YLGU's "are known for having a thick bill with a sharpely curved culmen, creating a blunt tipped bill". That is certainly not the case with the Hyannis bird. Its bill appar both shorter and and thinner than the ones on nearby HEGU's, and the culmen has a "gentle curve".
  • Having a white mirror in P9 would be OK for the nominate subspecies, but unlikely on 'atlantis'.

What's wrong with this bird being a Herring X Lesser Black-backed hybrid? In my opnion - not much, but the bright yellow legs. Hybrid HEGU X LBBG usually have yellowish/pinkish legs and feet.
 
Pictures below were digiscoped - Canon SD780IS through Swarovski 80mm HD STM 
  
Pictures below - Canon 50D w/Canon 100-400 IS