A Wild Goose Chase through the Literature

A Wild Goose Chase through the Literature…
by Nial Moores, June 9, 2012.
 

Brant, East Coast. Photo © Robin Newlin.

 

The Ramsar Convention COP 11 is coming up in July – time for Wetlands International (WI) to finish off the latest edition of the Waterbird Population estimates (Edition Five).  Like earlier editions, this resource (to be launched at the Ramsar COP) will cover all of the world’s Flyways and waterbirds. For each waterbird population (1,816 listed in the Fourth Edition!), it will provide estimates or an estimate range; a 1% figure for use in Ramsar site-designations; and a general description of distribution. Based on best knowledge and incorporating thousands of references and invited comments, it will be THE baseline with which to measure a site’s international importance for waterbirds and to flag conservation priorities. And this time, it will be posted online as an interactive resource – excellent!

It is all too-easy to underestimate how much time, effort and knowledge goes into developing such work. As part of Birds Korea’s genuinely modest contribution (and also as part of behind-the-scenes research on our next fully annotated checklist), several days have already been invested in providing information from Korea to this next edition. This has been time enough only to comment usefully on a few duck species (including flagging the plunge in population of Mallard Anas platyrhynchos) and on three geese: Greater White-fronted Anser albifrons, Lesser White-fronted Anser erythropus and Brant Branta bernicla nigricans.

One simple question asked by WI was whether or not Brant in Asia are from a single Japan/Korea/China population. Trying to answer this provides a great example of why this kind of work is so time-consuming and challenging (though made easier by some excellent online resources including the Google Maps Distance Calculator at: http://www.daftlogic.com/projects-google-maps-distance-calculator.htm).

Brant is a rare winter visitor to the ROK – with only one recorded nationwide in the 2011 winter census (MOE 2011).  It therefore seems to be a species on which little time needs to be spent by Korean organisations… However, it used to be less rare here. It was described by Austin (1948) as probably an “uncommon winter visitor” rather than a rarity.  A read of Park (2002) reveals that a flock of 138 Brant were found in the far southwest in 1974, and that 700 were seen in early 1984 at one site in the southeast. This led to an estimate of 1,000 or so on the ROK south coast at that time. Even as recently as 2001, 393 were recorded nationwide by the winter census (MOE 1999-2004).  The Brant is therefore a species that is now being found much less often and in smaller numbers in the ROK – despite the large increase in the number of birdwatchers and the greatly improved access to the coastal zone during the past 10-20 years. It is easy to conclude, therefore, that the Brant is decreasing in the ROK. It is reasonable to suggest too that tidal-flat reclamation and especially industrialisation of much of Gwangyang Bay and the outer Nakdong Estuary (the two sites that until recently supported the largest numbers of Brant in the ROK) will have contributed to this species’ worsening national conservation status.
 

Former Brant habitat, Nakdong Estuary. Image © Nial Moores.

 

However, even as the Brant has dwindled towards national extinction in the ROK, it has increased in Japan. According to Brazil (1991), Brant was formerly “a common winter visitor from southwest Hokkaido to as far south as Tokyo Bay” – at least until the mid-late 1800’s, when changes in gun-laws saw its demise. The Brant then remained “exceedingly scarce” in Japan, until a recovery started in the 1970s and 1980s. By 1982, three sites in Hokkaido and northern Honshu supported more than 100; and in October 1986 and 1987 no less than 5,000 were recorded in eastern Hokkaido.

Based on this, the Waterbird Population Estimates published in 2006 (Wetlands International 2006) stated that the East Asian non-breeding population of Brant was 5,000; that its breeding range was “E Siberia, Anadyr Basin eastward”; and that the wintering or core non-breeding area was “Coastal Kamchatka, Korea, Japan”.  Although not included in the formal notes, the belief seemed to be that Brant staged in Hokkaido in October and November, and then migrated on to Korea (and China?) for the mid-winter. This belief was fuelled by smaller numbers being found in the mid-winter than in October/November in Japan; mid-winter census counts in the ROK; and a mid-winter record of 1,200 at the Chang Shan Islands, Shandong Peninsula in 1993.

For the Fifth edition, the Asian Brant estimate is likely to be increased further – to a maximum of >8,000, based entirely on counts in the late 2000s in Japan. And yet, despite the increase in population in Japan, the Brant is declining in Korea.  And there is perhaps no evidence either of large flocks still wintering in China (if you have information to the contrary, please do mail us!).

Indeed, has there ever been any decent evidence of a migration route or link between Korean and Japanese Brant?  Such evidence might include:

1) A mirroring of decrease and/or increase in Korean and Japanese and Chinese Brant;
2) Records of flocks in intermediate sites (e.g. in south-western Japan);
3) Migration dates showing later arrival in winter and earlier departure in spring in Korea than shown by birds in Hokkaido (which presumably are much closer to northern breeding areas).

The present “goose search” through the scant literature fails to find any such evidence. Rather, it points to a very different conclusion.

As described above, there were more Brant found in the ROK than in Japan in the 1970s (even though survey effort was much higher in the latter nation); numbers found in the ROK peaked in the early-mid 1980s (when access to the coastal zone started to become easier), and then they soon declined to now tiny numbers. In contrast, Brant increased in the 1970s through to the mid-1980s in Japan, and that increase has continued to the present. Numbers of Brant in Japan are now eight times higher than the highest estimate in the ROK back in 1984.  If these birds are part of the same population, then why are larger numbers not now being found during migration, either in the ROK, in the DPRK (where according to Tomek [1999] the largest flock recorded to data was only 14, in December 1988 at Wonsan); in south-western Japan (where the Brant remains rare); or in China?

How about migration timing? Much fuller original data sets will exist. However, based on Brazil (1991), in 1985-1986 the latest Brant remained in eastern Hokkaido until April 13th. According to Park (2002), the 1974 Brant flock in the far southwest (c. 2000km WSW of Hokkaido) peaked at 138 on March 7th-8th, before falling to 111 on March 25th-26th. It is not known when the last birds were recorded. There is also a further record of 86 Brant in the ROK as late as May 3rd 2001 in the southeast. It seems unlikely that such Brant would migrate 1,600km from SE Korea to Hokkaido (three weeks after the vast majority have already departed there), and then a further 3,200km to easternmost Anadyr breeding grounds (a total distance of 4,800km) – especially when it is only 4,000- 4,200 km for the same birds to migrate directly or via the Okhotsk Sea toward breeding grounds mapped in Syroechkovskiy (2006). It seems even more implausible that Chinese Brant from Shandong and Liaoning (a location given for the species in Cheng 1987) would also choose to migrate 5,200km via Korea-Hokkaido-Anadyr, when they could reach the same Yakutian breeding grounds in only 3,750km.

Syroechkovskiy (2006) (pages 649-662 in the mammoth volume Waterbirds around the World, edited by Gerard Boere, Colin Galbraith and David Stroud) describes research on long-term declines in Arctic goose populations in eastern Asia. In Figure 9 (on page 659), he depicts both the changes in the distribution of three Brant populations and their presumed/proven migration routes. In the second half of the twentieth century, especially since the 1970s, the population of nominate Brant has moved east, and the population of far eastern nigricans (originating from North America) has moved west. There has been an increase in North American nigricans, and there has been a “drastic population decline” in Asian Brant. Now, the “Asian populations of nigricans are very small, poorly studied and close to extinction. The wintering sites in China are poorly known, and the breeding areas, which are thought to be on the lower Lena and Yana rivers (in Yakutia), have not been surveyed” (Syroechkovskiy 2006).

According to Figure 9, these Chinese (and Korean?) wintering areas are reached by one of two overland migration routes: direct from breeding areas to wintering areas; or historically, via a slightly longer route including the Okhostk Sea.

The same figure shows three additional migration routes, now used by far eastern nigricans: (1) northern Yakutia towards the Okohtsk Sea; (2) north-easternmost Russia  towards North America; and (3) Anadyr north-south along the Kamchatka coast and the Kurils to eastern Hokkaido. This latter route to Japan is approximately 3,000km in length. This route’s existence has been confirmed by observations of migrating Brant along the Kamchatka coast, and apparently by some marked birds, including some proven to breed in Alaska and winter in Japan.

The sensible conclusion, therefore, is that the increase in North American nigricans has resulted both in westward range extension into Far East Asia, and also the recent increase in Brant now wintering in Japan. In contrast, the decline in the Yakutian population of Brant has been mirrored by the decline in the ROK and presumably also a decline in the Chinese population.

Brant in East Asia therefore apparently do not belong to only one population. The Chinese and Korean wintering population likely breeds in Yakutia, and the Japanese wintering population likely breeds mostly in Anadyr, far to the east.  Of great concern to us here in the ROK is that the increase in Brant in northern Japan will therefore probably not result in any recovery of the Brant population in the ROK.

The Yakutia population of Brant is heading towards extinction. Clearly, it is time for the ROK and China to support conservation efforts of this highly-threatened population, both in the breeding and the non-breeding grounds. Otherwise, this population will disappear – and another beautiful species will be lost to both nations.

Brant at Nakdong, May 14, 2008. Image © Nial Moores.

 

References

Austin, O. L., Jr 1948. The birds of Korea. Bulletin of the Museum of Comparative Zoology,
Harvard University 101: 1-301.

Brazil, M. 1991. The Birds of Japan. Published by Helm.

Cheng T-H. 1987. A synopsis of the avifauna of China. Beijing: Science Press, and Hamburg and Berlin: Parey.

MOE (Ministry of Environment). 1999-2011. Annual Reports of the Winter Bird Census (in Korean).

Park, J-Y. 2002. Current status and distribution of birds in Korea. Department of Biology, Kyung Hee University, Seoul (unpublished thesis, in Korean).

Syroechkovskiy, Jr.E. E. 2006. Long-term declines in Arctic goose populations in eastern Asia, Pp. 649–662 in G. C. Boere, C. A. Galbraith and D. A. Stroud, eds.

Waterbirds around the world. Edinburgh, UK: The Stationery Office. Bird Conservation International (2011) 0:1–9. © BirdLife International, 2011 doi:10.1017/S0959270911000542

Tomek, T. 1999-2002. The birds of North Korea. Acta Zoologica Cracoviensia 42: 1-217; 45:1-235 (in English).

Wetlands International. 2006. Waterbird Population Estimates – Fourth Edition. Wetlands International, Wageningen, The Netherlands.

2 comments on “A Wild Goose Chase through the Literature

  1. Thanks to Dr Taej Mundkur of Wetlands International for forwarding on scans of “Status and Distribution of Pacific Brent Geese Branta bernicla nigricans Wintering in Japan” (Lane, S. & Miyabayashi Y. 1997. Wildfowl 48: 108-117. Published by the Wildfowl and Wetlands Trust).

    This important paper presents count data from Japan from 1970 and especially in the mid-1990s and observations from a survey of the ROK south coast between January 13th and 19th 1996. Japanese data for the period October 1989 and November 1995 showed that maximum numbers of Brant (up to 4,000) were “consistently recorded in October, but decreased rapidly thereafter.” The mean numbers counted at known wintering sites amounted to little more than 13% of the October average. Birds at known sites redistributed southward (largely to northern Honshu), and at these sites there had been no obvious change in number in mid-winter over a 25-year period. A mid-winter search for potential new sites along substantial stretches of the Japanese coast by the authors found only a small proportion of missing Brant. The authors therefore proposed, as a working hypothesis to be investigated by future researchers, that the majority of Brant continued southward to the ROK and then onto China for the mid-winter period. This possibility was supported by mid-winter presence in the ROK and by unconfirmed reports of between 500 and 5,000 Brant in “coastal regions between Qingdao and Shijiusuo, between Roncheng and Yantia, and at Laizhou Bay”. However, despite an intensive search of the southern coast of the (Korean) peninsula only 19 Brant were found – these in the Nakdong Estuary. And perhaps the reports from China remained largely unconfirmed?

    It would be wonderful to learn if large numbers of Brant have been discovered in the mid-winter in north-east Asia since this paper was published.

    Thanks in advance for sharing any counts or insights…

  2. Excellent work folks.

    I have few notes on Brent Goose in China.

    Brent Goose remains very poorly known in China and I’d think that its no better than a rare passage migrant and rare winter visitor to the coastal eastern provinces. Despite a marked increase in the number of skilled and active birders in the country its still not being reported annually. Some are no doubt overlooked – but probably not very many as the species is large and relatively conspicuous.

    20 years ago it probably occurred fairly regular in Liaoning, Hebei & Shandong but it appears to have declined since then. I would not think that it ever regularly occurred much further south than Shandong despite the fact that there are reports from most provinces down to Fujian & Taiwan (but note that it hasn’t, as far as I’m aware, been seen in either Shanghai or Zhejiang). Away from the coast the species has even been reported in Nei Mongol (see below) and even from Shaanxi (where it was included in an unpublished checklist of the Birds of the Shaanxi prepared by Richard Lewthwaite) but without knowing much more I’d treat both of these reports with caution.

    Note that there remain no reports of Brent Goose from relatively well watched Beijing.

    Personally I’ve seen it in China on just four occasions – but not for almost a decade!

    The more recent Chinese reports that I’m aware of are -

    Jilin
    Species was included in an unpublished checklist of the Birds of Xianghai NNR, Kaitong prepared by Sun Xiaohong (no date).

    Nei Mongol
    Recorded at one site in the extreme E. of the province according to Xurigan. Fauna Inner Mongolia. Vol. 3: Aves – Non-passeriformes. 2006. Inner Mongolia University Press. [In Chinese].

    Liaoning
    BAI Qingquan’s apparently seen it 5 or 6 times in Liaoning (pers. comm. to Paul Holt Jan. 2012) – the only record that he was able to remember at the time (other than the two detailed below) was of 15 or 16 birds in Donggang in late May of an unspecified year.

    One at Pikougang, Pulandian on 8 June 2007 [Bai Qingquan in 2007 China Bird Report] was a late record and the only record that year from anywhere in China.
    Five at Shicheng Liedao, Zhuanghe on 18 April 2008 [Bai Qingquan in 2008 China Bird Report] was the only record that year from anywhere in China.

    Hebei
    2 on the Sandflats, Beidaihe, Qinhuangdao on 30/3/1989 (Paul Holt).
    23 flew north off Lighthouse Point, Beidaihe, Qinhuangdao on 3/5/1994 (Paul Holt, Killian Mullarney, Martin Williams et al.)
    3 flew north off Lighthouse Point, Beidaihe, Qinhuangdao on 4/5/1994 (Paul Holt, Killian Mullarney, Martin Williams et al.)
    70 on Moai Island (near Happy Island), Leting on 18/5/1998 (Olsen, K-M., 2009 Beidaihe, Happy Island & Beijing, East China. [In Danish]. Unpublished internet report.)

    Shandong
    Despite the report of 1200 in the Chang Shan Islands in 1993 (Li et al.) the only two recent reports from that province that I’m aware of are -
    1 at Swan Lake, Rongcheng on 29/12/2001 (WWF excursion).
    4 at Hong Si Yan, Jiazhou Wan, Qingdao on the 29/12/2003 (Paul Holt).

    Hubei
    1 at Danjiang river, Danjiangkou on at least 29 & 30 Jan., 5 & 6 Feb. 2010 (Wang Xuefeng in China Bird Watch was described as being the first record for Hubei & the Yangtze Basin).

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>