Moerdijk Field Research 2005-2006

(last update: 14 August 2010)

In what way do Dutch Herring Gull resemble American Herring Gull (L. smithsonianus)? Starting point is the article in Dutch Birding by Bruce Mactavish & Peter Adriaens.

Winter American Herring Gull at Rochester, New Hampshire, USA, 26 December 2007, image Mike.

Peter and Bruce mention these features for adult birds:

.1: P10 should have a broad rectangular tongue, combined with a complete sub-terminal band; as is shown in the picture above.

.2: P5 should show a complete black "W".

.3: And a few extra’s, which add to the ID: bayonets (black continues along the feather edge, white 'moons' (tongue tips are white between grey centre and black sub-terminal band), and also a black "W" on P6.

First, for the Moerdijk birds, we have checked if the smithsonianus-pattern for P10 & P5 did occur in this population:

ad 1: A complete sub-terminal band on P10 can be found in 27% of the Dutch Herring Gulls (85 birds out of 319). But only 9 birds (3%) combine this complete sub-terminal band with a rectangular corner in the medial band.

ad 2: The P5 "W" was recorded in 26 birds.

The combination for P10 & P5 was more or less pretty okay in HG mVZ & HG oHE.

Below: Herring Gull mVZ:

Below: Herring Gull oHE:

Continue at: SECOND SET OF FEATURES for smithsonianus.