Scoring primary feathers of Lesser Black-backed Gulls

In my previous post, I talked about scoring the primary patterns of European Herring Gulls.

This post continues by discussing the Lesser Black-backed Gulls that were caught and ringed during that same session.

To repeat the characteristics that were scored:

1. Black on greater primary coverts
2. Number of primaries with black pigmentation
3. P10 and P9 primary pattern:
I: No mirror
II: Mirror on one web
III: Full subterminal black band, mirror on both webs
IV: Subterminal black present, but band broken
V: No subterminal black, mirror completely merged with tip.
VI: ‘Thayeri’ pattern, medial band not reaching the feather-edge of the inner web (long grey tongue, joining the white mirror)
4. P5 primary pattern: Not scored.
5. Primary moult score. See explanation.

#1 can serve as an indication of age (large amounts of black are usually only present in sub-adults), whereas #2, 3, and 5 are thought to be possible characteristics for separating different subspecies.

Lesser Black-backed Gulls (Larus fuscus graellsii)

Characteristics of interest are marked in blue.

Individual ringed as White S*/Black

Left and right wing pattern of Lesser Black-baced Gull ringed as White S*/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts: none.
  2. Number of primaries with black pigmentation:
    Left wing: 7  (P4-P10)
    Right wing: 6 (P5-P10) (P6 missing)
  3. P10 and P9 primary pattern:
    P10: III – Full subterminal black band, mirror on both webs
    P9 (left wing): III – Full subterminal black band, mirror on both webs
    P9 (right wing):II – Mirror on one web
  4. Primary moult score:
    Left wing: 8 (P1 and P2 almost fully grown).
    Right wing: 0 (P1 and P2 old).

A very interesting individual with distinct differences in both wings.

Most noticeable are the gaps in the right wing with P6 missing and what looks like secondaries S1 and S2 missing as well. I believe that this is unlikely to be moult-related, but I don’t have a proper explanation for it either.

The left wing does show proper wing moult with P1 and P2 almost fully grown, whereas P1 and P2 seem to be still present in the right wing.

Small differences in markings exist as well: the small white mirror on the inner web of P9 and the small black mark on the outer web of P5 in the left wing  which are both absent in the right wing.

It’s almost as if both wings belong to different individuals.

Individual ringed as White S6/Black

Wing pattern of Lesser Black-baced Gull ringed as White S6/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts: none.
  2. Number of primaries with black pigmentation: 8 (P3-P10)
  3. P10 and P9 primary pattern:
    P10: III – Full subterminal black band, mirror on both webs
    P9: I – No mirror
  4. Primary moult score:  0 (all primaries present)

An individual with black markings down to P3, something which is not uncommon in Lesser Black-backed Gulls.

Individual ringed as White T0/Black

Wing pattern of Lesser Black-baced Gull ringed as White T0/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts: none.
  2. Number of primaries with black pigmentation: 7 (P4-P10)
  3. P10 and P9 primary pattern:
    P10: V – No subterminal black, mirror completely merged with tip.
    P9: III – Full subterminal black band, mirror on both webs
  4. Primary moult score:  0 (all primaries present)

Individual ringed as White T2/Black

Wing pattern of Lesser Black-baced Gull ringed as White T2/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts: none.
  2. Number of primaries with black pigmentation: 7 (P4-P10)
  3. P10 and P9 primary pattern:
    P10: III – Full subterminal black band, mirror on both webs
    P9: III – Full subterminal black band, mirror on both webs
  4. Primary moult score:  8 (P1 fully grown, P2 almost fully grown)

Individual ringed as White T4/Black

Wing pattern of Lesser Black-baced Gull ringed as White T4/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts: present on some of the outer webs.
  2. Number of primaries with black pigmentation: 7 (P4-P10)
  3. P10 and P9 primary pattern:
    P10: IV – Subterminal black present, but band broken
    P9: III – Full subterminal black band, mirror on both webs
  4. Primary moult score:  0 (all primaries present)

Individual ringed as White TG/Black

Wing pattern of Lesser Black-baced Gull ringed as White TG/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts: sharply demarcated markings on some of the inner webs.
  2. Number of primaries with black pigmentation: 7 (P4-P10)
  3. P10 and P9 primary pattern:
    P10: IV – Subterminal black present, but band broken
    P9: III – Full subterminal black band, mirror on both webs
  4. Primary moult score:  0 (all primaries present)

Individual ringed as White TK/Black

Wing pattern of Lesser Black-baced Gull ringed as White TK/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts: distinct markings on some of the inner webs.
  2. Number of primaries with black pigmentation: 7 (P4-P10)
  3. P10 and P9 primary pattern:
    P10: III – Full subterminal black band, mirror on both webs
    P9: I – No mirror
  4. Primary moult score:  0 (all primaries present)

Individual ringed as White TK/Black

Wing pattern of Lesser Black-baced Gull ringed as White TL/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts:  markings on some of the inner webs.
  2. Number of primaries with black pigmentation: 8 (P3-P10)
  3. P10 and P9 primary pattern:
    P10: III – Full subterminal black band, mirror on both webs
    P9: I – No mirror
  4. Primary moult score:  0 (all primaries present)

Individual ringed as White TV/Black

Wing pattern of Lesser Black-baced Gull ringed as White TV/Black. The Netherlands, 6 May 2012.

  1. Black on greater primary coverts:  none.
  2. Number of primaries with black pigmentation: 6 (P5-P10)
  3. P10 and P9 primary pattern:
    P10: V – No subterminal black, mirror completely merged with tip.
    P9: III – Full subterminal black band, mirror on both webs
  4. Primary moult score:  7 (P1 half grown, P2 almost fully grown)

Discussion
Compared to the wing tip patterns of the Herring Gulls discussed in my previous post, the patterns of the Lesser Black-backed Gulls are far less diverse. What has been most interesting for me to learn is the presence of black markings on the greater primary coverts in adults, something which I had not realized before and only thought to apply to sub-adult.

It was also interesting to see that some individual had already started moulting their primaries, something that I wasn’t expecting for another few weeks.

All-in-all, this has been a great learning experience for me.

References

Phenotypic characteristics and moult commencement in Dutch Herring & Lesser Black-Backed Gulls, Muusse, M., Muusse, T., Buijs, R.-J., Altenburg, R., Gibbins, C. and Luijendijk, B.-J., SEABIRD 24 (2011): 42–59.

2 thoughts on “Scoring primary feathers of Lesser Black-backed Gulls

  1. This bird White S*/Black, you present it as it had back on 7 primaries on the left wing and only 5 on the right wing. Would it not be better to present it as it have 7 with black on left and 6 on right? The only difference between the two wing patterns is the small black spot on P4, considering that P6 it is missing on the left wing.

    Alternative primary pattern;
    Left wing: 7 (P4-P10)
    Right wing: 6 (P5-P10) (P6 missing)

    From what we can see your LBBGs start moult 1 month before our Norwegian urban breeding LBBGs, and 2 month beefore our birds breeding out in the colonies in the archipelago. Very interesting 🙂

    Very good blog!

    Best wishes,

    Morten

    • Hi Morten,

      Many thanks for your comments!
      Looking at the way I scored the pattern of the right wing in White S*/Black, I agree with you that the only difference is in P4 and that P6 is missing. I’ve updated the post 🙂

      Best regards,

      Maarten

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