Adult European Herring Green Y.BRD with immature pattern on tail feathers (again) – 20150427

By Maarten van Kleinwee April 27, 2015 larus argentatus larus argentatus argenteus adult

Last year an adult European Herring Gull Larus argentatus argenteus was caught while breeding in the gull colony of IJmuiden (Forteiland), the Netherlands, and ringed as Green Y.BRD. To our surprise, it showed central tail feathers with a sub-adult pattern:

Today we came across Green Y.BRD again in the same breeding colony and much to our surprise it again showed the same pattern on the central tail feathers:

2 thoughts on “Adult European Herring Green Y.BRD with immature pattern on tail feathers (again) – 20150427”

Phil

April 27, 2015 at 19:53 Reply

Is there a plausible reason why an adult gull might continue to grow subadult feathers? If it was a hormonal thing (for example), I’d expect more feathers to be affected.
- Maarten van Kleinwee
  
  April 27, 2015 at 20:47 Reply
  
  I don’t know Phil. All I know is that it is seen very rarely in adult gulls. Unfortunately we don’t know its exact age.