Are bare patches in Herring Gulls a sign of old age?

One of the ways by which to distinguish 27-year old Herring Gull ZDGA from other Herring Gulls (apart from the color ring that he is wearing of course), are the bare patches on the right side of the neck and face that appear when he is moulting to winter (basic) plumage.

European Herring Gull, (Black D)/Green A, Leiden, The Netherlands, 6 July 2013. At this time of year a bare patch can be seen in his right neck, thereby clearly showing his age.

European Herring Gull, (Black D)/Green A, Leiden, The Netherlands, 6 July 2013. At this time of year a bare patch can be seen in his right neck.

ZDGA in its 24th calendar year. Leiden, The Netherlands, 15 Augus 2009.

ZDGA in its 24th calendar year. Leiden, The Netherlands, 15 Augus 2009.

ZDGA in its 25th-calendar year. The bare patches were visible during the months of July through September. Leiden, The Netherlands, 21 August 2010.

ZDGA in its 25th-calendar year. The bare patches were visible during the months of July through September. Leiden, The Netherlands, 21 August 2010.

The question is: can we treat this as a characteristic of gulls of a certain age?

As far as ZDGA is concerned, we know that he showed these patches in 2009 (his 24th calendar year), the year when I first encountered him. Unfortunately, no data containing references to his appearance exists of him before that time so we don’t know when this started to show. Going by the size of the bare patch though, I would expect that it would have taken a few years to develop.

Sightings are rare

My personal sightings of such individuals are few and far between. Apart from ZDGA, I have only seen 2 other individuals over the last 5 years showing similar characteristics.

Bird #1

European Herring Gull, presumed to be of old age, based on the bare patch in the neck. Leiden, The Netherlands, 29 July 2010.

European Herring Gull, presumed to be of old age, based on the bare patch in the neck. Leiden, The Netherlands, 29 July 2010.

Bird #2

European Herring Gull, presumed to be of old age, based on the bare patch in the neck. Leiden, The Netherlands, 6  July 2013.

European Herring Gull, presumed to be of old age, based on the bare patch in the neck. Leiden, The Netherlands, 6 July 2013.

Is it health related?

The fact that all my 3 individuals were observed in July at a time when they were actively moulting to basic plumage indicates to me that it is not a health issue. If it was, you would expect it to be seen throughout the year.

Also, ZDGA is a healthy individual and has been ever since I saw him, showing active and regular moult sequences each year, in line with other individuals. And come September, the bare patch is fully replaced by a nice set of new feathers.

In September when the body feathers have been fully replaced, ZDGA shows no bare patch anymore. Leiden, The Netherlands, 11 September 2010.

In September when the body feathers have been fully replaced, ZDGA shows no bare patch anymore. Leiden, The Netherlands, 11 September 2010.

Conclusion

I do believe therefore that these bare patches are typical of old Herring Gulls, and that they are at a minimum 18 – 20 years old, but possibly older.

I am aware though that not all old Herring Gulls show such bare patches: I’ve seen a photo of a known (color-ringed) Dutch 24-year old Herring Gull (so the same age as ZDGA in 2009) in July showing no bare patches at all.

But I do believe that when you see a Herring Gull showing such bare patches that it is roughly 20 years or older.

More examples needed

To confirm my theory, I would love to know about other observations of ringed Herring Gulls showing these characteristics, preferably in the form of photographs. If you know of any, please let me know.

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9 thoughts on “Are bare patches in Herring Gulls a sign of old age?

  1. Cool writeup. Have you thought about posting to the BirdingGulls mailing list (if there’s anyone still active on there) about this? There used to be loads of gull enthusiasts on it…

    I’ve seen gulls with small bare patches around the eyes occasionally (nothing more than that), but I’d just assumed that these were due to fighting or scratching too much because of parasites.

  2. When you see those gull fights on YouTube, there are often clumps of feathers pulled out from the face, head and neck, though. Could be a combination of things…

    Just thinking too – perhaps these particular gulls have bald patches all the time, but they are hidden once the new feathers are fully grown?

    • Yes, it could well be that these patches are there all the time but are hidden for most of the year.
      I’m quite fortune to be able to follow this individual of known age over multiple seasons. It’s a shame that no other gulls of the same project are still around or have lost their rings. There are quite a few ongoing projects in Europe at the moment so it is just a matter of waiting until those gulls are of the right age so that we can check them πŸ™‚

  3. I saved a baby gull today. πŸ™‚ A Lesser Black-back, I believe. Looked near full-size, but its head plumage was still a bit downy and it could only flutter around a little bit. If I caught it easily, then a fox or dog certainly could’ve caught it, or a gull-hater armed with a shovel. There didn’t seem to be a mother gull around (if there was, I’d have known about it when I went near the chick, I guess), so I took it to an wildlife rescue place… Now it’s #27 in his baby gull flock…

      • Cute little bird. I didn’t take any pictures though – because I didn’t want to scare him any more than he was already. At the rescue, there was a young one that seemed to be more interested in humans than it was with the other gulls. I think that some children had been hand-feeding it for a few days before they brought it in. Just ran up and squeaked at the people who walked past the enclosure, like it would for its mother. That’s how you end up with a pet. πŸ™‚

  4. On the subject of baby gulls, I think that this has to be one of the cutest videos on YouTube:

    I know from personal experience with Budgerigars that birds don’t like being thrown into the air by humans to encourage them to fly…

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