Three Australian leg-flagged Roseate Terns found at Caiyu Archipelago of SE Fujian, China

During 2007–2009, people of the Xiamen Bird-watching Society, when undertaking regular surveys on waterbirds occurring along the Fujian coast including those offshore islands, had observed, for five times, some marked individuals of the Roseate Tern (Sterna dougallii) at Caiyu Archipelago close to Gulei town of Zhangpu County, far south Fujian of SE China (Fig. 1), and the details are shown below.

Figure  1.  Caiyu Archipelago (Source: Google earth)

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Assuming that that is the same bird on Photos 2 and 3 whilst so is bird shown on Photos 1 and 5, there were at least three marked Roseate Terns observed during the three years from 2007 to 2009.

  Photo 1.  31 July 2007, at Tujiao, a metal ring found banded on tarsus of its left leg (by Qingxian LIN)

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  Photo 2.  5 July 2008, at Shengbeiyu, a metal ring on its left tarsus and a flag on the right (by Zhi LIN)

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  Photo 3.  15 May 2009, at Niaoweiyu, a metal ring on its left tarsus and a flag on the right (by Zhi LIN)

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  Photo 4.  15 May 2009, at Niaoweiyu, a flag on its left tarsus while uncertain of the right (by Zhi LIN)

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  Photo 5.  25 July 2009, at Niaoweiyu, a mental ring on its left tarsus (by Weifu ZHENG)

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Via checking, we learned that the three leg-flagged terns were marked by people of the Australasian Wader Studies Group (AWSG), and, according to the feedback from Heather and Clive Minton of AWSG (Fig. 2):

Figure  2.  A sketch map showing the localities where those leg-flagged terns were marked and then observed

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"This bird was flagged at Swain Reefs, Great Barrier Reef, Queensland, approximate co-ordinates 21deg 50min S, 152deg 0min E, which uses the flag combination White, as an adult in Jan or Feb since 2002.

"The re-sighting was a distance of approximately 6289 km, with a bearing of 322 degrees, from the marking location.

"The Swain Reefs is an area of 2000 km² of reefs and small coral cays at the southern end of the Great Barrier Reef in Queensland, Australia. Up to 5000 non-breeding Roseate Terns (Sterna dougallii) have been observed in the area during July, and 25000 in January or February. We used a small cannon net to capture birds that we then banded and leg-flagged; we also collected biometric and moult data from appropriate samples. We captured 368 Roseate Terns in July of 1999, 2000 and 2001, and 3044 in January of 2002 and 2003. We determined that at least some Roseate Terns of the local Queensland breeding population (S. d. gracilis) from colonies on the Capricornia Cays occur in the Swain Reefs during July. Among the January captures were 44 birds carrying Japanese leg-bands and three carrying Taiwanese leg-bands. This is the first evidence that Asian-breeding Roseate Terns over-winter in the southern hemisphere. Subsequent sightings of flagged birds have occurred in the Japanese breeding colonies (with one recapture) and in breeding colonies in the southern Great Barrier Reef. Using plumage and moult characteristics we determined that 60% (15000 birds) of the Roseate Terns present in Swain Reefs in January belong to the Asian population (S. d. bangsi), 1.5% (375 birds) to the local population (S. d. gracilis), and the remaining 38% (9500 birds) were of unknown breeding origin."

Though now it is still uncertain who had ringed those tern birds, as shown on Photos 1, 2, 3 and 5, from a very conservative point of view, at least one of those leg-flagged terns has shown to us that it is already over 6 or 7 years old, as very recently Heather and Clive mentioned that "the last Roseate Tern banding/flagging was done as recently as January 2009". Furthermore, according to the re-sighting record of the Relict Gull (Larus relictus) that we banded on the Ordos upland of W Inner Mongolia, the longest time the banded bird has far known survived is over 10 years (Photo 6).

  Photo 6.  The Relict Gull banded in June 1998 and re-sighted in June 2009 (by Fenqi HE)

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These records might be useful and helpful for further estimating the life circle as well as the length of generation of those gulls and terns appearing and breeding along the SE Chinese coast, such as the Black-tailed Gull (Larus crassirostris), the Great Crested Tern (Sterna bergii), the Chinese Crested Tern (Sterna bernsteini), etc.