Moerdijk Field Research 2005-2006

(last update: 14 August 2010)

Roland-Jan Buijs
Theo Muusse
Mars Muusse


Age, origin & sex
Retrapped Birds
Upperparts Greytone
Black on Primary Coverts
Black on Primaries
P10 and P9 Patterns
P5 Pattern
Red & Black on Bill
Iris & Orbital Ring
Primary Moult

Larus argenatus argenteus, Moerdijk, the Netherlands.

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.