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Figure 15: Heuglini moult is late on average, which is also illustrated by many pictures taken in winter in W India, Arabian peninsular, E African coast. Buzun also checked on primary moult on the breeding grounds, and concluded that there is a slight differerence between the islands and the tundra. For Russia, moult commencement takes place between 20 June – 20 July. By mid-July, he scored primary moult for both populations: Mid July islands: 25% moulted P3. Mid July tundra: 30% moulted P4 or higher.
We have no data on moult commencement from Moerdijk for this period (June-July), as we ringed in May and first week June.
But we visited Maasvlakte (Netherlands), Zeebrugge (Belgium) and Ijmuiden (Netherlands) in the summer period in 2003. We scored ringed birds only. Adults in this sample are 5+cy Lesser Black-backed Gulls. In 2003 we scored over 1000 birds (n = 1114). The birds were ringed in the UK, Belgium, Holland, Germany, Denmark, Norway and Sweden.
Figure 16: Heuglini moult for June-July. Data for heuglini are from Buzun 2002. Data on 5+cy LBBG are from 2003. Red triangle on top is moult commencement period according to Buzun (20 June – 20 July).
Figure 17: Heuglini moult early-September. Data Heuglini from Visa Rauste (1999). Intermedius and graellsii from 2003.
Figure 18: Heuglini moult late… as do some graellsii!
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