Dr. Nial Moores, July 22nd 2015 (with further edits on July 27th)
Even while details of the first finder wait to be fully confirmed (please!), it is clear that the Bar-headed Goose Anser indicus in Hadong, Jeollanam Province this summer provides an excellent opportunity to review and improve the ways in which Birds Korea tries to assess records of those species that are considered to occur naturally here in the ROK but which are also sometimes found in captivity within Korea or the wider region. We welcome your suggestions on how to improve this process.
To date, in the absence of formal national or regional records committees, most decisions have been made based largely on time-consuming informal communication within Korea and with expert birders across the wider region, in order to determine (ultimately, often subjectively…):
- Possible evidence of captivity (including abnormal bare parts or feather wear / moult; bands; or clipped primaries);
- Regional presence or absence, either in the wild or in collections, of the taxon;
- The migratory nature of the taxon (including whether it is considered usually sedentary, or a short range or long-range migrant, and the most likely timing of occurrence here);
- The suitability of location and habitat;
- The bird’s behaviour (i.e. whether the bird “behaves like a wild bird” or not);
- The age of the individual (in the understanding that adults are generally much less prone to vagrancy than less experienced younger birds);
- Supporting evidence suggesting the possibility of vagrancy (e.g. other out-of-range records of the same taxon or of similar species within the region during the same period; or severe weather events).
More formal processes are required, if records are to be assessed more objectively and with greater consistency in ways that can be understood by future generations of birders and ornithologists.
By way of example, below is the application of these seven criteria to the record of this year’s over-summering Bar-headed Goose, a species that is “endemic at high altitudes in central and southern Asia” (Wurdinger 2005).
1. Evidence of Captivity
Online images of the Hadong bird show that in July it had full primaries; no bands; a fairly typical-looking bill shape; and generally good bare part and feather condition, with the exception of one or more of the tertials and some of the wing coverts on the right side of the bird.
Reviewing available images (including of the Ganghwa bird, kindly forwarded on July 26th by Park Jong-Gil), the first bird recorded in Korea and the one at Ganghwa are both perhaps too distant to determine minor plumage anomalies with confidence. However, both were clearly unringed and showed plumages that match what might be expected in wild birds.
Therefore, none of these three Bar-headed Geese seem to show any obvious evidence of captivity.
2. Regional Presence of Absence
- The species is already included in Category One of our Checklist and on other national checklists primarily on the basis of one (adult-like or adult bird) found and photographed by Dr. Lee Kisup at the Han-Imjin Estuary in March 2003. The bird was present from at least March 15th and 29th, apparently associating with a large flock of Swan Goose and White-naped Crane. Various strands of research suggest that these Swan Geese probably over-wintered in the Yangtze flood-plain, so it seems likely that this bird had also earlier overwintered out-of-range in southern China and migrated north with them.
- A second probable Bar-headed Goose, an immature bird, was seen briefly by Prof. Robin Newlin at Seosan on November 2nd 2008 among many thousands of grey geese.
- A third (perhaps unidentified?) bird that most resembled a First-winter Bar-headed Goose was also photographed at distance in flight with some grey geese (at present, I am unable to re-find this image, so do not know the date, location or even the name of the photographer: does anyone else remember it?).
- A fourth bird, an adult, was photographed on Ganghwa Island in among a flock of Greater White-fronted Goose on December 10th 2013, and the record was included with date in Park (2014).
At most, therefore, the species has been recorded two to four times previously in the ROK (so is assessed by Birds Korea as V2): with single birds in late March, perhaps in November and again in December.
Although some are probably kept in zoos, we do not yet know of any free-flying feral Bar-headed Geese here in the ROK. If the Hadong bird is feral, it therefore most likely came from elsewhere in the region.
Closest to our region, the species breeds naturally on the Qinghai-Tibetan Plateau and in parts of Mongolia and southernmost Russia. Since the mid-2000s, it has also been bred in captivity and released back into the wild (or traded and consumed commercially). This reintroduction scheme (as far as can be told) appears to relate to birds hatched from eggs taken from and then released back at local lakes on the Qinghai-Tibetan Plateau approximately 2,500km from Korea.
The species appears to be rare to the east of its natural range, either as a feral bird or in the wild.
- Top Shanghai birder Zhang Lin (of SBS in China) has yet to see the species in eastern China. He reports that there are a few records of wild birds “in north China and central China (Dongting Lake, Hubei etc)” (Zhang Lin in lit. July 2015).
- In the Beijing area, Terry Townshend of Birding Beijing fame knows of no Bar-headed Geese in collections (TT: in lit. July 2015).
- According to research by Paul Holt (PH: in lit. to TT in 2013), there had been approximately 14 records in total in the Beijing area up to mid-2013, including one seen by PH and TT on June 1st 2013. At least nine of these records were in the first half of the year. Most of these Beijing records are considered likely to refer to wild birds, though one at the Old Summer Palace in central Beijing on 11 June 2012 was considered by PH as “more likely to have been feral than many others” presumably because of its location and date.
- Tim Edelsten (TE) has traced images of presumably single feral Bar-headed Geese in city parks in both Shanghai (in 2009) and Beijing, with one photographed with feral Black Swans in Beijing, again at the Old Summer Palace, on April 28th 2014 (TE in lit. July 2015). Perhaps this latter bird remained on this same city lake in Beijing for two or more years?
- To the east of Korea, the species is not listed as an introduced species in Japan (unlike e.g. the moffitti subspecies of Canada Goose), so it appears that there are very few if any free-flying feral Bar-headed Geese there, even though it is known to be present in some collections. According to Brazil (1991) and OSJ (2012) the species has occurred at least three times in the wild in Japan: once in Honshu (September 1st 1972); once on Chichijima (February 6th – March or April 1986); and once on Taramajima (October 2006). These three records, if genuinely of wild birds, prove that vagrant Bar-headed Geese can occasionally migrate long distances over sea, and turn up in the most unexpected of locations (including small tropical islands!), even at a time of year (beginning of September) when other grey geese are absent.
3. Migratory nature of the taxon
The Bar-headed Goose is migratory, with some of the northern breeders leap-frogging the population that breeds on the Qinghai-Tibetan Plateau, to winter in India.
We cannot know when the Hadong bird arrived, only when it was first seen, which is now suggested to be May 26th (TE via Shim Kyu-Sik) or perhaps earlier.
And review of specialist literature suggests that a wild Bar-headed Goose in spring is perhaps most likely to arrive in Korea in either May or June (not in March or April). This is because the most likely source for a wild bird is the population that breeds in Mongolia, to the northwest of Korea. The larger population that breeds on the Qingai-Tibetan Plateau to our west generally migrates only 1300-1500km each way (Zhang et al. 2011) and the distance to Korea from Qinghai Lake is almost twice the typical distance flown by this population during migration. There is also as yet perhaps no confirmation of migration of birds from that region to Korea.
In contrast, satellite tracking and marked birds confirm that many species migrate regularly between Mongolia and Korea (e.g. Whooper Swan, Mongolian Gull and Cinereous Vulture). The Mongolian population of Bar-headed Goose also undertakes the longest migration of all Bar-headed Geese, with some birds flying 5,000km along a southwest-northeast axis (Batbayar 2013), including over the Himalaya.
The main northward migration period of the Bar-headed Goose, a species that breeds in the Asian interior at high altitude, is (understandably!) quite late. Satellite tracking shows that marked Bar-headed Geese breeding in Mongolia crossed the Himalaya between March 15th and May 6th; with the median arrival date at breeding sites in Mongolia of May 9th. One tracked bird even arrived back on the breeding grounds as late as June 13th (Batbayar 2013).
It seems reasonable to assume that most vagrant wild birds will be inexperienced migrants (i.e. immature birds). Immatures, especially those separated from flocks of the same species, would likely require more time at stopovers to refuel, and would also experience less urgency to continue on to the breeding grounds, when compared to adults. This would further delay their arrival in eastern China, Korea or Japan.
Wild spring vagrants to Korea therefore would seem most likely to arrive here in mid-May or June rather than e.g. in February or March, when most of the Mongolian-breeding population has not even crossed the Himalaya.
There is at the least too a plausible explanation for eastward displacement of long-range migrant Bar-headed Geese to northeast China and Korea in May. Winds and weather systems north of the Himalaya typically move from west to east often at very high speeds during spring, as in early May 2015. Severe weather experienced during northward migration during or just after birds had crossed the Himalaya would likely be able to drift birds eastward towards eastern China and Korea. Inexperienced migrants (e.g. young birds), once displaced, might then fail to re-orientate correctly. Instead, they might well continue their migration on a similar northeastward axis as part of northward migration with other geese; or as lone birds well to the east of their intended route.
If a displaced bird flew for 5,000km from northern India it could / would then reach Korea.
4. Suitability of Location and Habitat
According to specialist literature, the Bar-headed Goose uses a range of habitats during migration with stopover sites being “mainly lake, marshland, and other shallow waters, but some are farmlands” (Zhang et al. 2011). Some of the Bar-headed Geese wintering in northern Myanmar roosted on sand-banks in the Ayeyarwady River (Van der Ven et al. 2010).
The Hadong bird was found in an area of extensive bird-rich wet rice-fields, with a small lake, lying within a few hundred meters of a wide stretch of the ROK’s fifth largest river, the Seomjin. The Seomjin River has wide sand-banks and some riparian vegetation, including grasses. Moreover, Hadong lies at the foot of the highest mountains in the south of the mainland and is only c.10-15km from the south coast.
The Hadong bird is therefore in apparently suitable habitat in a reasonable location for a migrant, displaced or otherwise, on northward migration.
As the area also lies ~5,000km from northern India (the maximum migration distance regularly undertaken by the species), its geographical location might well stimulate a displaced Bar-headed Goose to over-summer.
The Han-Imjin bird was also in a suitable location, able to feed on mud-flat vegetation and to roost with other geese on sand-banks in the river. It was likely stimulated to continue migration by the northward departure of large numbers of other geese and e.g. the emergence of spring vegetation. The Ganghwa bird was in wet rice-fields, and perhaps was also likely stimulated to migrate southward by the grey geese it was with.
- Although the Hadong bird often allows/ allowed (very) close approach, on July 18th it was seen to flush 1km when disturbed by a passing vehicle blowing its horn (Matt Poll pers com July 2015).
- There appears to be no artificial feeding of waterbirds in Hadong that might help to sustain an escaped bird that was accustomed to / dependent on such feeding.
- The bird was watched feeding “naturally”, largely concealed, in an area of wet rice-fields that seemed attractive to other bird species and to e.g. dragon-flies (suggesting a low level of pesticide use).
- Notably, Bar-headed Geese in the wild often appear to be less wary than many other geese species, both within the breeding range in Tibet (Zhang Lin in lit. July 2015) and in Mongolia (Tim Edelsten in lit. July 2015).
Perhaps nothing in the behaviour of the Hadong bird would be considered exceptional in a wild bird (or a feral one!).
The Han-Imjin bird was feeding (and roosting) in a wetland without public access, mixed in with other geese, as might be expected of a wild goose.
Is the Hadong bird a full adult or a Second Calendar-year bird?
Bar-headed Goose Anser indicus , Hadong, July 18th 2015 © Nial Moores. Are the patterned, contrasty tertials and the less solid, black look to some of the head and neck markings indicative of immaturity?
The species is believed to take three or four years to reach sexual maturity. Birds of the year, however, are said to start to moult into an adult plumage only 115-125 days after hatching (Wurdinger 2005).
Are the yellowish tones to part of the bill, the brownish tones to many of the areas which appear to be blacker in breeding adults, and the contrast in the tertials of the Hadong bird perhaps indicative of immaturity? Or are such features also shown by some adults?
Images of the Han-Imjin bird are too small to enable ageing. It was either an adult or an adult-type.
The Ganghwa bird looks very similar in plumage to the Hadong bird; but appears to have had tertials that were perhaps less contrasty, closer to some online images of presumed adults.
7. Supporting Evidence of Vagrancy in 2015
This spring there were several records of out-of-range Bar-headed Geese in Beijing, including what appears to have been the first multiple arrival of the species in May (TT in lit. July 2015):
- The first one was seen in Beijing on April 4th.
- This was followed a month later by one at Miyun Reservoir on May 4th with a Swan Goose.
- On May 9th, there were three at Miyun and one at Shahe Reservoir.
- On the 10th, four were at Miyun Reservoir (the highest known count to date for Beijing) with three still there on May 11th .
If the five or six Bar-headed Geese that reached Beijing in May were the result of earlier eastward displacement of wild birds followed by stopover and then continued migration towards the northeast (as proposed above), then it seems quite reasonable for one (or more) geese also to have been displaced further east still, to reach Korea this May.
To sum up:
- We cannot know whether the Hadong bird is an escape from a zoo or collection or whether it is a wild bird that arrived here under its own power.
- Although widely considered to be an escape, the bird presently seems to meet all the criteria for assessment as a naturally-occurring wild bird. So are these criteria and the assessment sufficient?
- Moreover, on information accessed for this post, it could easily be argued that the timing and location of this Hadong bird are rather more plausible than any of the three accepted records for Japan (one on September 1st, when the species should still be close to the breeding area; and two on small tropical Pacific islands).
- And although there are records of this species in Beijing in March, the late date of the Hadong bird also seems rather more plausible than the dates of the other records in the ROK.
In light of the above, if the Hadong bird is assumed to be an escape or feral bird then how should the March 2003 Bar-headed Goose be assessed? And why?
And what too of records of other species sometimes held in collections? For example, last winter’s adult Demoiselle Crane in Cheorwon, with its unreadable leg-rings? Or this summer’s Demoiselle Crane in Japan (via Neil Davidson, in lit. 2015)?
Although most Japanese records of Demoiselle Crane have been in winter, the species has also been recorded before in northern Honshu in early June 1922 and in Hokkaido in May and June 1974 (Brazil 1991). How to assess therefore what might be the first July record for Japan of Demoiselle Crane, a trans-Himalaya migrant, just like the Bar-headed Goose?
The presence of an unknown number of captive or free-flying feral birds within East Asia, while still far fewer than e.g. in western Europe, can only create growing uncertainty over out-of-range or unseasonal records of an increasing number of species. These species include e.g. pelicans, Demoiselle Crane and Bar-headed Goose and several landbirds. Ongoing attempts at “restoration” (including of Crested Ibis and Mute Swan, neither of which were ever recorded breeding in the wild in the ROK) look set to complicate such assessments even further.
If you have ideas on how to improve the objectivity and efficiency of this massively time-consuming (and ultimately subjective!) assessment process, please do let us know: Thank you.
With thanks already to Matt Poll, Jason Loghry, Ha Jeong Mun, Tim Edelsten, Dr. Shim Kyu-Sik, Terry Townshend, Zhang Lin, Richard Klim, Sean Minns and Neil Davidson.
- Batbayar, N. 2013. Breeding and Migration Ecology of Bar-headed Goose Anser indicus and Swan Goose Anser cygnoides in Asia. Doctoral thesis, University of Oklahoma.
- Brazil, M. 1991. The Birds of Japan. Published by Helm.
- Brazil, M. 2009. Birds of East Asia. Helm Field Guides.
- OSJ. 2012. Check-List of Japanese Birds, 7th Revised Edition. Published by the Ornithological Society of Japan, 2012. MS Excel file accessed in July 2015 at: http://ornithology.jp/osj/japanese/katsudo/Publications/Checklist7_e.html
- Park J-G. 2014. Identification Guide to Birds of Korea. Checklist of Organisms in Korea 12 (series). Nature and Ecology Publication (in Korean)
- Van der Ven., J. , Gole, P. & G. Ouweneel. 2010. Bar-headed Geese Anser indicus: notes from breeding and wintering areas. Goose Bulletin. Issue 10- May 2010.Goose Specialist Group of Wetlands International and IUCN. http://www.geese.org/gsg/goose_bulletin/Goose%20Bulletin%20issue10.pdf
- Wurdinger, I. 2005. Bar-headed Goose Anser indicus. In Kear, J. (ed). Ducks, Geese and Swans, Volume One. Oxford University Press.
- Zhang Y., Hao M., Takekawa, J., Fumin Lei, Baoping Yan, Prosser, D., Douglas, D. Xing Z., & S. Newman. 2011. Tracking the Autumn Migration of the Bar-Headed Goose (Anser indicus) with Satellite Telemetry and Relationship to Environmental Conditions. Research Article, International Journal of Zoology, Vol. 11 Article ID 323847. http://dx.doi.org/10.1155/2011/323847 Accessed in July 2015 at: http://www.hindawi.com/journals/ijz/2011/323847/