Great Cormorant - Grote Aalscholver

Great Cormorant

Grote Aalscholver

Phalacrocorax c. carbo

Pictures: Teus Luijendijk

This bird was discovered wintering on a gravel pit near Roermond in Limburg, the South-East province of The Netherlands. Not quite the area where one would expect this subspecies, which is supposedly more bound to (rocky) sea coasts than the common dutch breeding subspecies sinensis. It was not only identified by its larger size and somewhat different jizz, but also by the obvious colour ring on the left leg, showing that it originated from the British Isles (Abberton Reservoir, Colchester, Essex to be precise).

Subspecific identification of Great Cormorants has recently been treated in Dutch Birding (van den Berg et al. 2000). In this article was stated that the shape of the gape line can be used to distinguish between the nominate subspecies carbo and the continental sinensis. However, it might be that the matter is not that simple: Dirk Moerbeek presents some nice digital camera pictures on his website that suggest that this character may in fact be not all that decisive. The gapeline shape may vary to some extent, possibly resulting in continental birds that show a gapeline, supposedly typical for carbo. Perhaps also the opposite may occur. There simply does not seem to be enough data available to conclude on the validity of this field character. I personally share his criticism and invite everyone to take a closer look at Cormorants, in order to obtain more information on the fenotypical characters of these two taxa.
The bird shown here was discovered 4 February 2000, but it later appeared that it already had been noticed 6 September 1998. It will probably stay there well into 2001.

  Great Cormorant  -  Grote Aalscholver  Phalacrocorax c. carbo   adult;  videograbs (320x), contrast somewhat enhanced.
  Heel Li, The Netherlands, 19 November 2000.

 

Reference: Van den Berg AB, Van Loon A & McGeehan A 2000. Aalscholver met kenmerken van Grote Aalscholver te Heel in februari 2000. Dutch Birding 22: 21-25.


Copyright ©Teus Luijendijk 2000