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.

The combination P10 with P5 as mentioned by Bruce Mactavish & Peter Adriaens (and see on previous page) could turn out to be diagnostic for smithsonianus. However, these two birds from Moerdijk on the previous page (mVZ & oHE) may come close to what is defined as the primary patterns for smithsonianus. Bruce & Peter continue their article for cases where P5 has no complete band. In such birds, there should be a following set of five features:

a: P10 again the broad rectangular tongue, combined with a complete sub-terminal band.

b: P9 has no mirror or a mirror only on the innerweb.

c: P7 (& P8) show bayonets.

d: P8 has a white tongue-tip on the innerweb.

e: P6 shows a "W" sub-terminal band.

Considering the vast variation in possible patterns on the outwing in Moerdijk Herring Gulls, as is shown on the pages of this website, one may wonder if such a combination of features may occur in (probably a very small portion of) Dutch breeding Herring Gulls as well. Below, some example birds which come close regarding this set of five.

Below: Herring Gull oPL:

Below: Herring Gull m39:

Below: Herring Gull m42: