Larus cachinnans

(last update: February 16, 2013)

Greg Neubauer
Marcin Przymencki
Albert de Jong
Mars Muusse


cachinnans plumages

Larus cachinnans 21P1 8CY-9CY, February 2013 & April 2014, Minden, Germany & Zastow Karczmiski, Poland. Picture: Łukasz Bednarz & Armin Deutsch.

Green 21P1 and metal PLG DN-19496, ringed as pullus cachinnans on May 08 2006 at Wloclawek, central Poland (52°39' N, 19°08' E).

21P1 8-5-2006 RZ. Wisla, Wloclawek 52°39' N 19°08' E
21P1 13-2-2013 Deponie Pohlsche Heide 52°23' N 08°46' E

below: Larus cachinnans 21P1 9CY, April 17 2014, Zastow Karczmiski, Poland. Picture: Łukasz Bednarz.

Please visit Łukasz's BLOG for beautiful drawings and up-to-date gull news from eastern Poland: Wildlife art and illustration

Larus cachinnans 9cy, probably female. Here in the breeding colony near Zastow Karczmiski (Vistula River).

below: Larus cachinnans 21P1 8CY, February 13 2013, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E). Picture: Armin Deutsch.

Probably female, with much black on outerwebs of P8-P10.

Below, table 1 is repeated to score this bird in adult plumage. Traits scores are in italic + bold. Total score is 2 (by Mars Muusse), open for discussion, but will always be far away from hybrid zone.
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)  measured 2,82 Mars Muusse from picture 
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

Fig. 6. Sum trait scores for adult Caspian Larus cachinnans and Herring Gulls L argentatus, and hybrids. Scores are calculated by summing individual trait score values. The figure shows the percentage of individuals in the sample with a given sum value. Numbers in parentheses are the minimum and maximum values recorded.
From the Rarities Committee's files - Identification of Caspian Gull. Part 2: phenotypic variability and the field characteristics of hybrids, by Chris Gibbins, Grzegorz Neubauer and Brian Small, IN: BB 104/2011.