Hybrid from the Netherlands

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marsmuusse
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Hybrid from the Netherlands

Post by marsmuusse » Thu May 30, 2013 9:15 am

Location: roof top breeding at police station Katwijk aan Zee (52.12.04.30 N ; 04.24.51.43 O). Address: Piet Heinlaan 140, Katwijk.
Ringer: Roland-Jan Buijs / Buijs Eco Consult.
Measurements & Photography: Roland-Jan Buijs / Buijs Eco Consult & Jeroen Nagtegaal / Hogeschool Larenstein.
Date: May 28 2013.

GREY TONE:
In the Netherlands, Herring Gull upper-parts is clearly paler than upper-parts of Lesser Black-backed Gulls, without any overlap in grey tone. The modal grey tone for the Herring Gulls sampled was 5 (range 3-7) and for Lesser Black backed Gull 11 (range 8-15). Samples are from the Moerdijk colony 2005 & 2006, sample size in Herring Gull: n = 292 and Lesser Black-backed Gull: n = 888. Measurements based on Agfa Grey Scale 0-20.

Grey tone of 8,5 in black K.B rules out typical Larus argentatus argenteus Herring Gull, breeding in the Netherlands, and also a deep coral red orbital ring and red gape is extremely rare (<0,5%) in breeding Herring Gull the Netherlands.

ORBITAL RING & GAPE:
Almost all Herring Gulls showed orange orbital rings (94%), with only 18 birds having yellow and one bird (HG NLA 5.363.004) a red orbital ring. Coral red is 'the classic' colour for Lesser Black-backed Gulls. Four Lesser Black-backed Gulls scored orange (LBBG yS8, y13, oC9, oTX), with all other individuals having red orbital rings. Sample for Herring: 284, and sample Lesser Black-backed Gull: 919.

All single characteristics in black K.B could just fit in Dutch Lesser Black-Backed Gull Larus fuscus graellsii, but the combination of features is highly unlike to occur simultaneous in a single bird:
- pale grey upper-parts (graellsii upperpart < grey 9,0 = 0,23%, n=888)
- no red nor black on upper mandible (graellsii no red on upper mandible = 39%), (graellsii no black on upper mandible = 19%). (graellsii no black on lower mandible = 32%)
- 6 primaries with sub-terminal black (graellsii primaries with sub-terminal black < 7 = 23%, n=931 in all breeding birds, n=869 in 5+CY birds / full adults)
- much white in P10 wing-tip. (graellsii no sub-terminal black or broken band on P10 = 17,5%, n=931)
- no black on primary coverts. (graellsii no black on coverts = 24%)

'Straw yellow' legs can be found in adult Larus fuscus graellsii, but saturated yellow legs are by far more common (no %).

Given the low %'s of occurrence of single features, and the low probability they occur simultaneously in a single graellsii bird (though some feature may correlate, like wing-tip pattern), the possibility this bird black K.B may be hybrid is real.
Then, speculation starts about parentage. This really is only speculation, as we know from ringed birds some offsprings don't show much similarity to any of the parents. Anyhow, michahellis x graellsii (several, about 30, mixed pairs annually in the Netherlands) would probably have rich yellow legs, red on upper mandible, not this much white on P10 tip, and also not such a long grey tongue on P7-P8 (grey running far down to feather tip, leaving only a narrow medial band). Also in this hybrid option, grey tone may be expected slightly darker.
Probably argenteus is involved, which has been expected to hybridise with graellsii in the past, but nowadays, with large populations of both species, hybridisation doesn't seem to occur anymore (at least, it is not documented over the last years as far as I know). Evidence of occurrence is green E433, hybrid pullus ringed on June 29 1995. This is different for argenteus x michahellis, and maybe this is also the most likely option for black K.B. It may explain the straw yellow legs, 8,5 greytone on upperparts, relatively much white in wing-tip and lack of red on the upper mandible. Also, looking closer at the legs it appears the legs are indeed yellowish, but feet seem to be more pinkish.
Attachments
P1030437.JPG
Iris speckling = 0%. Orbital ring = coral red. Gape = coral red. Black on upper mandible = NO. Red on upper mandible = NO. Black on lower mandible = NO. Red on lower mandible = NO.
P1030437.JPG (714.56 KiB) Viewed 4260 times
P1030436.JPG
Iris speckling = 0%. Orbital ring = coral red. Gape = coral red. Black on upper mandible = NO. Red on upper mandible = NO. Black on lower mandible = NO. Red on lower mandible = NO.
P1030436.JPG (656.37 KiB) Viewed 4260 times
P1030435.JPG
Measurement in Photoshop with colour chart. Reference yellow is 91% yellow, 15% cyan. Note yellow hue on legs, not really saturated, rather "straw yellow". Measured: shin is somewhat whitish yellow (highest Yellow component 61%) en calf more saturated straw yellow (highest yellow component 78% at backside of knee).
P1030435.JPG (698.75 KiB) Viewed 4260 times
P1030429.JPG
Sub-terminal black on P10 = "broken" (no black on outerweb). Mirror on P10 = on both webs. Sub-terminal black on P9 = "full band". Mirror on P10 = on both webs. Sub-terminal black on P5 = "full band".
P1030429.JPG (798.13 KiB) Viewed 4260 times
P1030428.JPG
Number of primaries with sub-terminal black = 6 (P10-P5). Black on primary coverts = NO.
P1030428.JPG (541.37 KiB) Viewed 4260 times
P1030427.JPG
Note short grey tongue on P10 with diffuse transition into black. Sub-terminal black on P10 = "broken" (no black on outerweb).
P1030427.JPG (501.87 KiB) Viewed 4260 times
P1030433.JPG
Grey tone = 8,5. (on 20 steps scale).
P1030433.JPG (624.55 KiB) Viewed 4260 times
P1030432.JPG
Measurement in Photoshop Grey Mode: Grey tone = 8,5-9,0. (on 20 steps scale).
P1030432.JPG (441.69 KiB) Viewed 4260 times
P1030430.JPG
metal tibia 5424660 and black darvic tibia K.B (yellow inscription). Ringer: Roland-Jan Buijs / Buijs Eco Consult. Note yellow hue on legs, not really saturated, rather "straw yellow".
P1030430.JPG (738.64 KiB) Viewed 4260 times
P1030426.JPG
metal tibia 5424660 and black darvic tibia K.B (yellow inscription). Ringer: Roland-Jan Buijs / Buijs Eco Consult. Note yellow hue on legs, not really saturated, rather "straw yellow".
P1030426.JPG (669.53 KiB) Viewed 4260 times
P1030431.JPG
Iris speckling = 0%. Orbital ring = coral red. Gape = coral red.
P1030431.JPG (545.21 KiB) Viewed 4260 times
Last edited by marsmuusse on Thu May 30, 2013 8:02 pm, edited 4 times in total.

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marsmuusse
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Re: Hybrid from the Netherlands

Post by marsmuusse » Thu May 30, 2013 9:40 am

Green EV65, June 21 1997 pullus ringed at Dintelhaven-Maasvlakte, the Netherlands. Trapped at the nest at Moerdijk breeding colony, May 14 2005.
Location: industrial complex Moerdijk (51.41.41.41 N ; 04.36.06.06 O). Address: TatraPak Moerdijk BV, Oostelijke Randweg 48, Moerdijk
Ringer: Roland-Jan Buijs / Buijs Eco Consult.
Measurements & Photography: Roland-Jan Buijs / Buijs Eco Consult & Mars + Theo Muusse.
Date: May 14 2005.

More pictures of green EV65 as 4CY bird: http://www.gull-research.org/hg/hg4cy/hybridev65.htm
Attachments
greenev65_1929.jpg
Breeding gulls, Moerdijk, the Netherlands: grey tone 11 in LBBG oJH female wing 425mm (left), grey tone 8.5 in 9CY hybrid m35 (centre, ringed pullus green EV65 at Dintelhaven-Maasvlakte in 1992) & grey tone 6.0 in HG m36 male wing 446mm (right).
greenev65_1929.jpg (861.77 KiB) Viewed 4259 times
greenev65_1927.jpg
Grey tone 8.5 in 9CY hybrid m35 (left, ringed pullus green EV65 at Dintelhaven-Maasvlakte in 1992) & grey tone 6.0 in HG m36 male wing 446mm (right).
greenev65_1927.jpg (824.38 KiB) Viewed 4259 times
greenev65_1933.jpg
Grey tone 8.5 in 9CY hybrid m35 (top, ringed pullus green EV65 at Dintelhaven-Maasvlakte in 1992) & grey tone 11 in LBBG oJH female wing 425mm (bottom).
greenev65_1933.jpg (796.89 KiB) Viewed 4259 times
greenev65_1931.jpg
Grey tone 8.5 in 9CY hybrid m35 (top, ringed pullus green EV65 at Dintelhaven-Maasvlakte in 1992) & grey tone 6.0 in HG m36 male wing 446mm (bottom).
greenev65_1931.jpg (687.89 KiB) Viewed 4259 times
greenev65_1914.jpg
Head + Bill measurement: 112,9 mm. Female. Orange hue on upper mandible, colour may even be considered to represent 'true red'. Black on upper and lower mandible. Orbital ring and gape red. Speckling category 0-1%.
greenev65_1914.jpg (641.94 KiB) Viewed 4259 times
greenev65_1922.jpg
Legs not rich, deep, saturated yellow, but 'dull pale yellow'.
greenev65_1922.jpg (735.42 KiB) Viewed 4259 times
greenev65_1915.jpg
P10 mirror on both webs. P10 sub-terminal band broken. P9 mirror on both webs. P9 full sub-terminal band. P5 broken sub-terminal band.
greenev65_1915.jpg (876.42 KiB) Viewed 4259 times
greenev65_1910.jpg
old green EV65, new ring now tibia mint 35 & metal tarsus 5.414.910.
greenev65_1910.jpg (647.56 KiB) Viewed 4259 times
greenev65_1912.jpg
grey tone 8,5.
greenev65_1912.jpg (702.77 KiB) Viewed 4259 times
greenev65_1919.jpg
Wing: 431 mm. Primaries with sub-terminal black = 6 (P5-P10). Black on primary coverts = NO.
greenev65_1919.jpg (856.47 KiB) Viewed 4259 times
greenev65_1918.jpg
Primaries with sub-terminal black = 6 (P5-P10). Black on primary coverts = NO.
greenev65_1918.jpg (831.64 KiB) Viewed 4259 times
greenev65_1920.jpg
division between grey and black = diffuse.
greenev65_1920.jpg (719.34 KiB) Viewed 4259 times
Last edited by marsmuusse on Thu May 30, 2013 7:51 pm, edited 1 time in total.

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marsmuusse
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Re: Hybrid from the Netherlands

Post by marsmuusse » Thu May 30, 2013 6:10 pm

Orange EP29, ringed as pullus on June 23 1997 offspring of male michahellis (orange EAY8) x female Herring Gull; ringed at Neeltje Jans, the Netherlands. Trapped at the nest at Neeltje Jans breeding colony, May 07 2006. New rings: tarsus metal 6146972 and darvic orange with black code PA.
Location: artificial dunes at Neeltje Jans (51.37.54.41 N ; 03.41.49.06 O). Address: Hoogh Plaetweg, Neeltje Jans.
Ringer: Roland-Jan Buijs / Buijs Eco Consult / Pim Wolf / Theo Muusse.
Measurements & Photography: Roland-Jan Buijs / Buijs Eco Consult & Theo Muusse.
Date: May 07 2006.

F1 hybrid from male Larus michahellis x female Larus argentatus argenteus. Adult male michahellis trapped at nest at Neeltje Jans, ringed EAY8 on May 30 1997. Pictures of this male michahellis EAY8: http://www.gull-research.org/gbbg/gbbg0 ... ranfe.html
More picture of EP29: http://www.gull-research.org/hg/hg4cy/hybridep29.htm
More pictures of EP30, from same nest: http://www.gull-research.org/hg/hg3cy/hybridep30.htm
Attachments
oPA_6428.jpg
Red on upper mandible = YES. Black on lower mandible = YES. Black on upper mandible = YES. Gape is orange. Orbital ring is orange-red. Iris speckling = 0-1%.
oPA_6428.jpg (574.01 KiB) Viewed 4246 times
oPA_6430.jpg
Red on upper mandible = YES. Black on lower mandible = YES. Black on upper mandible = YES. Gape is orange. Orbital ring is orange-red. Iris speckling = 0-1%.
oPA_6430.jpg (489.16 KiB) Viewed 4246 times
oPA_6437.jpg
Division between black and grey on underside P10 = diffuse.
oPA_6437.jpg (663.22 KiB) Viewed 4246 times
oPA_6433.jpg
P10 mirror = on both webs. P10 sub-teminal band = 'broken' (triangles). P9 mirror = only on innerweb. P9 sub-terminal band = 'full band'. P5 sub-terminal band = 'full band'. Number of primaries with sub-terminal black = 6 (P5-P10). Black on primary coverts = NO. PMS = 1 from max=50 (1000000000)
oPA_6433.jpg (670.54 KiB) Viewed 4246 times
oPA_6431.jpg
new rings: tarsus metal 6146972 and darvic orange with black code PA. Legs yellow.
oPA_6431.jpg (630.05 KiB) Viewed 4246 times
oPA_6404.jpg
still with old ring, but not for long...
oPA_6404.jpg (551.21 KiB) Viewed 4246 times

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marsmuusse
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Re: Hybrid from the Netherlands

Post by marsmuusse » Thu May 30, 2013 8:31 pm

An interesting bird: female AH6, photographed with partner graellsii BWAD at Zeebrugge on May 03 2003. It was ringed as pullus on June 20 1992 at Maasvlakte, The Netherlands, a hybrid Yellow-legged (mother) x Herring Gull (father). Green ring on right leg, with white code "AH6". In 2001, this bird was paired with a Lesser Black-backed Gull, and successfully reared three young (backcrosses). It returned to the Zeebrugge colony in spring 2003. Strangely enough, its upperparts are darker grey than in Yellow-legged Gull, and it did not choose one of the parent species to mate with. Note also the very broad white scapular and tertial crescents.

More pictures of green AH6 and discussion of this bird: http://www.gull-research.org/lbbgjanmay/admaygah6.htm
See also Surfbirds, article by Peter Adriaens: http://www.surfbirds.com/ID%20Articles/ ... 21203.html
Attachments
DSC00934bwad.jpg
DSC00934bwad.jpg (927.57 KiB) Viewed 4237 times
DSC00931ah6green.jpg
DSC00931ah6green.jpg (814.03 KiB) Viewed 4237 times

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alfosse
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Re: Hybrid from the Netherlands

Post by alfosse » Fri May 31, 2013 7:02 am

More pictures of green AH6 and discussion of this bird: http://www.gull-research.org/lbbgjanmay/admaygah6.htm
You'll find also the life-history (at least the data I'm aware of) of green AH6 on
http://baguage.lpo-anjou.org/AH6.htm

Note that the old green ring has been removed in 2007 and that the bird is now blue G·JAL.
Alain Fossé
Angers, France

adriaens
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Re: Hybrid from the Netherlands

Post by adriaens » Sat Jun 08, 2013 2:49 pm

Indeed the green ring 'AH6' has been replaced by a blue one, code 'G.JAL'.
More (recent) information on and photos of this bird can be found in http://gull-research.org/papers/papers5 ... ep2012.pdf

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