Larus cachinnans

(last update: February 16, 2013)

Coordinator:
Peter Adriaens (Belgium)
Ies Meulmeester (Netherlands)

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cachinnans plumages

Larus cachinnans hybrid 4CY & 5CY 07P2 December 2009 & January 2010, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E).
Picture: Armin Deutsch.

Green ring from Poland. Ringed as a chick on May 20 2006 in Wloclawek reservoir, central Poland (52°39'N, 19°08'E). Mother known as hybrid Caspian x Herring, father unknown.

This bird is very Herring-like and has a high score (20). The P10 pattern, with a short tongue and thick black band within the white tip, is outside that seen in any pure Caspian in our sample. Perhaps the only Caspian sign is seen in the bill, which is relatively slim with only a slight gonydeal angle.

Bird is discussed using table 1, below the pictures.

below: cachinnans hybrid 4CY 07P2 December 17 2009, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E). Picture: Armin Deutsch.

No full band on P5, full sub/terminal band on P10 and much black in outerwing.

above: cachinnans hybrid 4CY 07P2 December 17 2009, Pohlsche Heide, Germany. Picture: Armin Deutsch.

below: cachinnans hybrid 5CY 07P2 January 14 2010, Pohlsche Heide, Germany. Picture: Armin Deutsch.

below: cachinnans hybrid 5CY 07P2 January 14 2010, Pohlsche Heide, Germany. Picture: Armin Deutsch.

Very much Herring Gull-like.

Below, table 1 is repeated to score this bird. All traits can be scored, the partial scores are in italic + bold.

Total score is 20 (scored by authors; score is 19 by Mars Muusse), but open for discussion.
Trait Score Description
P10 overall pattern: white to black ratio 0 less black than white
1 approximately equal black and white
2 more black than white
P10: white tip 0 clear white, no signs of black
1 small dark spots on one or both webs
2 incomplete subterminal bar (two large black spots, one on each web or an unconnected bar, broken in the middle)
3 complete subterminal bar
P10: tongue 0 white or whitish
1 paler than mantle
2 same shade as mantle
P5: extent of black 0 black on both webs connected, forming band, black of equal depth on each web
1 black on both webs connected, forming band, black on outer web deeper than inner
2 black on both webs, but isolated spots (= incomplete bar)
3 black on outer web only
4 no black
P4: extent of black 0 black on both webs
1 black on one web only
2 no black
Iris peppering 0 dark-looking, >50% covered by dark spotting/peppering
1 moderately dark, with 10-50% of the area spotted
2 single or very few dark spots (area < 10%)
3 no dark spotting on iris
Eye-ring colour 0 dark/deep orange to red 
1 pale to moderately orange 
2 yellow
Bill shape 0 very long and slim, with little/no visible gonydeal angle (L:D ratio >2.8) 
1 slim, slight gonydeal angle (ratio 2.4-2.79)
2 intermediate (ratio 2.0-2.39) 
3 short and deep, well-marked gonydeal angle (ratio <2.0) 
Leg length 0 long
1 moderately long 
2 short