Larus cachinnans

(last update: February 16, 2013)

Greg Neubauer
Marcin Przymencki
Albert de Jong
Mars Muusse


cachinnans plumages

Larus cachinnans 6CY female PCVU May 12 2011, Kozielno - Paczkow, Opolskie Poland. Picture Michal Rycak.

Green 36P3 & metal PLG DN-21322 was ringed on May 14 2007 as pullus at Wloclawek by Greg Neubauer. Both parents are unknown. This bird was photographed in Germany by Armin Deutsch and appeared very argentatus-like. Follow the link for details.

Now as 6CY female it was caught breeding at the nest on May 12 2011 and re-ringed with yellow PCVU. Its measurements tell it is a pure cachinnans female. Location: Kozielno, Paczkow, S-SW Poland, (50°29' N,  16°58' E).

The total sum score of traits is 11 (score from pictures, by Mars Muusse, not in the field), which is just okay for cachinnans (4-12), not good for argentatus (12-20), but could also apply to hybrid (9-20). See figure below images.

Below, table 1 is repeated to score this bird. Not all traits can be scored, the partial scores are in italic + bold.

Total score is 11 (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)  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 (from images of 36P3
2 short