large Japanese cormorants*

Japanese Cormorant | Great Cormorant
ウミウ | カワウ

The two bigger Great Cormorant (Phalacrocorax carbo) and Japanese - or Temminck's - Cormorant cause quite a bit of ID-trouble.
Subtle differences are recognized but not always easily applied in the field.
Because I too struggle often, I will give the main ID-paper links here... in the hope to get this problem fixed sometime soon and to help others maybe to ID their Japanese larger Phalacrocorax records.

difference JC en GC
(Gular Pouch is the yellow bare skin just behind the bill, touching the eye)

Great Cormorant
Gular Pouch angle = 85°* and straight sides (more or less) CONVEX

Japanese Cormorant
Gular Pouch angle = <85°, sharp angle and curved sides (more or less) CONCAVE

gular pouch angle in Western Europe
On the gular pouch difference between ssp carbo and ssp sinensis
http://web.tiscali.it/cormorants/pdf/Stuart_ardea2004.pdf
Gular pouch wise I would think Japanese cormorants in general are closer to c.carbo?

the 85-degree angle has been determined for sinensis, the sister ssp from the continent, which up to now is considered not distinguishable from hanedae in the field.

Temminck's <> Great Cormorant
http://www.birdskoreablog.org/?p=14250
https://www.dutchbirding.nl/journal/pdf/DB_1999_21_1.pdf
http://www.biodic.go.jp/kawau/d_hogokanri/hunt_leaflet.pdf

general features to be checked:
Phalacrocorax capillatus
PRO
broad and high ending white cheek (not a very reliable feature)
angular yellow patch
slightly more gentle , sloping head.

Location: both species may occur inland and in coastal areas. I don't think that is a safe IDentifier. General opinion though apparently is that capillatus is more tied to the coast.
edit 2021: i have come across very few (if any) shots of temminckś inland. But that could be the bias playing up. Confirmed Temminck are mostly at sea or on/near the seaboard.

the hue of adult breeding bird mantles is often suggested to be a distinguishing feature. As the perception of colour greatly depends on the lighting I suppose it is a feature that should probably be used as a supporting feature rather than a prime identifier (but that is just a layman speaking, perhaps)

*
NB. I don't claim scientific status for these scribbles. It's just a reminder of what to look for.

NB. feel free to comment, add links to (Japanese) texts or....

On the gular pouch difference between ssp carbo and ssp sinensis
http://web.tiscali.it/cormorants/pdf/Stuart_ardea2004.pdf
Gular pouch wise I would think Japanese cormorants in general are closer to c.carbo?

thanks in advance.
Gerben

Publicado el noviembre 20, 2019 11:35 TARDE por housecrows housecrows

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