Another email in from Nial Moores
He’s replying to this request, from two epidemiologists at British Columbia Centre for Disease Control, Vancouver, British Columbia, Canada
– in Quinghai province (China) in mid-April to mid-May 2005
– in neighbouring Xinjiang province (China) in mid-May to mid-June
– in southwestern Siberia in mid-July (18 Jul 2005 1st reported onset)
– in Kazakhstan in mid-July (22 Jul 2005 1st reported onset).
Looking at a map of the region, it is telling that these areas are in
a rather direct north-west line from each other. Moreover, Qinghai province is also in line with Thailand and Northern Vietnam.
Is it possible that a particular species of migratory bird travels
this north-west route in the spring/summer and could be spreading the virus? We would be interested to know if there are (local?) experts with knowledge about specific Asian avian migratory routes who might be able to help pinpoint one or more avian species that could be spreading the virus. This would be interesting to know and would contribute to our understanding — and perhaps to our ability to control — these avian influenza outbreaks.
You ask: Is there a species that basically just keeps migrating north west ward during the sping and summer.
This question to me seems to have three elements:
(1) Does the timing of outbreaks really seem to follow a Northwest line?
Well, looking at the map (if accurate) at http://www.recombinomics.com/H5N1_Map_2005_Tomsk.html the pattern seems rather more erratic than that to me.
(2) Do any species migrate that way (either north-west through the spring or summer or erratically through the spring and summer)?
In short, no.
(3) Do individuals of any species migrate between all affected areas, with presence coinciding with outbreaks?
None, as far as I know.
By way of longer explanation, this kind of migration pattern would be an extremely odd and wasteful behavior for any species.
Generally, as in North America as in Asia, most bird species that breed in the northern hemisphere do so in months between March and August/September. The further north they nest, the later the migrants will arrive on the breeding territory, which will still be occupied for a number of weeks or months. In the far north, most summer visitors will lay eggs and fledge young in May-June-first half of July, for example.
In some cases, such as in some shorebird species (peeps, curlews, plovers etc), failed breeders, after migrating all the way to northern breeding areas (getting there in late May), will then start soon to migrate south again, with increasing numbers of such adults arriving back at key staging areas (often coastal) as early as mid to late July (eg as far south as Korea).
In a few other species, individuals will not complete their northward migration in spring and will therefore not go as far as the full adults, summering at a site well south of their breeding grounds.
For the majority of all species, they simply (and logically) occupy breeding areas for several weeks/ months (between e.g May and July), after which many species undertake some form of moult before southward migration. In the case of many ducks and geese species, most individuals are effectively flightless or have restricted powers of flight in mid-summer. All parts of this biological cycle are fairly regular and predictable, evolved to meet given environmental conditions.
Of especial interest in this regard is the Bar-headed Goose, presented by some “authorities” as a likely vector.
Please note, beyond not migrating as far north as Novosibirisk, the following expert account on Bar-headed Goose:
“Spring migration starts in March in India and Pakistan; arrives at Kok Nor Mar-Apr; and northern Gobi and Pamir mid-May.”
Egg-laying in “early to mid-may in Tianshan; incubation 27-30 days…breeding pairs with goslings start wing moult 24-28 days after young hatch; both adults lose all primaries and secondaries within 24 hr. Able to fly 32-25 days later with young; by then, primaries 80% of normal length, and within 40-45 days, wings fully grown”
“Autumn migration starts in northern breeding areas in late Aug, in Pamir end Sept”.
(Wurdinger I.,, 2005: in J. Kear (editor), Ducks, Geese and Swans. Bird Families of the World. Oxford University Press.)
This gives us approximate spring/summer dates thus:
Arrival at e.g. Qinghai in late April/early May
Egg-laying and incubation;
Early June-mid-June hatching of goslings;
Early July-late July wing moult of adults starts, when these geese are FLIGHTLESS until early August/mid-August, and capable of longer flights only by the end of August.
End of August capable of longer flights
“Autumn migration starts in northern breeding areas in late Aug, in Pamir end sept”.
(Odd that some “authorities” are apparently suggesting that the geese during this flightless period have been flying north to Siberia and west to Kazakhstan!!!).
As to the third element of your question, looking at the distribution of outbreaks (since 1997 rather than just this year) and the distribution of species, I think probably the only species, species-group that might have occured in all of these areas when and where H5N 1 is implicated or likely to be implicated (from Indonesia to Japan, to Korea to China to Mongolia to Kazakhstan) would be: (1) “ducks”; (2) Grey Heron Ardea cinerea, and (3) “shorebirds” (peeps, curlews, plovers).
( I would very much welcome correction from Taej, Martin or others if appropriate.)
It is of course essential to put and KEEP the above paragraph in context.
1) As noted before, only one species of northern duck regularly migrates to Indonesia, albeit quite scarcely, the Garganey Anas querquedula. However, it does not occur in Korea or Japan in winter for example, and breeds north of the area where this summer’s outbreaks have occurred. There is no duck species occurring in all areas – and certainly therefore no individuals fanning out missile like from some central Asian breeding ground (!).
2) As it is a very widespread species in Europe and Asia, likely only the Grey Heron would be found in northernmost, southermost, westernmost and easternmost sites where outbreaks have occurred in the past few years, but although a partial migrant I am not aware of any evidence (or even possibility) of a Grey Heron migrating the whole distance from e.g Indonesia north to Russia. Seems extremely unlikely.
This would appear to be very wasteful behavior for such a large species and not supported as far as I am aware by any banding recoveries.(correct Taej?)
I am not sure of the exact status of Grey Heron in more tropical areas, but I would imagine largely resident, with populations in some areas supplemented by northern breeders wintering southward. I do not believe any have been found infected? And of course, if this was a significant vector species, surely it would have already infected birds in many other countries to which it migrates (eg in South Asia) where the disease has yet to be detected.
3) Shorebirds/peeps etc are a very large family; with many species; and many different migration strategies.
Firstly, NO shorebirds, individuals or species, would be moving around nomad-like to each site spreading disease.
However, there are so many species, in some their migrations are so lengthy, and as they are found in every country of the region during migration or as non-breeders, it is possible that some individuals of one or other species could perhaps have been in the same area at the same time as each outbreak.
Several of these shorebird species migrate the length of the Flyway to Alaska and down to Indonesia and to Australia and New Zealand, to many areas where there have been outbreaks, and even more where there have been none. Some of these shorebird species are generally considered (on the basis of extensive published research) to be among the most adapted of bird species in terms of energetics. This is believed to make them among the most susceptible to disease. It has been suggested that one adaptation to this susceptibility is that many such species of shorebird nest in the Far North or in mountains (NB: a general belief simply put is that such species have low resistance to disease, and this kind of Arctic environment is less conducive to disease outbreaks than the tropics and lowlands). Although generally susceptible to disease, no shorebirds have yet been found that are infected that I am aware of.
In summary to parts 2 and 3 of your question:
1) In NO case that I know of does a species arrive in the Northern Hemisphere at a breeding area, then during the breeding season disperse both west, north and east of there.
2) No species will likely have been present at the sites of all outbreaks; even no species group can be obviously associated (certainly not geese that do not migrate to Indonesia, are rare in Viet nam and northern Thailand; not wild ducks; not gulls). In no case, therefore can a single wild species be obviously implicated, linking the sites together.
3) The spread and timing of the disease really does not match the behaviour and movement of wild migrant birds (not only this summer, but also in previous outbreaks).
I have not yet heard whether there were domestic ducks at all of these recent outbreak sites? Or poultry? Or whether the route of spread better matches highway and human transport systems? I wonder too if the same vectors are likely even responsible in each outbreak?
For the record, I have little knowledge of disease, with no medical background, so I would be reluctant to dismiss wild birds involvement in the spread of the disease. It is of course possible that some species might have been involved as vectors in one or more of these outbreaks (in the case of Qinghai, timing of outbreak for example could coincide with arrivals of wild ducks coming from SE China, where also many domestic ducks are kept in natural wetlands; if infected in SE China but still capable of migration and shedding the virus — itself possible?- they would then mix with Bar-headed Geese and Great Black-headed Gull arriving from the southwest. Not only are thery both species arriving from areas where they would likely have no resistance to the disease (S Asia), but they are also both species that nest at Qinghai in colonies). However, I believe from what I have read that there is no proof yet that wild birds are vectors, despite very many claims. And even if the viral strain is the same at several of these sites, common sense dictates that the virus likely did not arrive at each site in an identical manner (unless through human influence).
In contrast, some outbreaks have been confined to poultry houses and in areas with few wild waterbirds. It seems extremely obvious, therefore, that the MAJOR cause of spread has been and very likely will continue to be poultry (here including domestic ducks): not only are they far more abundant overall than wild waterbirds, they are maintained in an environment where disease is easiest to spread and evolve; they are the only bird species found in probably each and every area; and the only species known to move throughout the region, but not freely into neighboring regions (such as Europe and North America).
It is clear therefore that two major steps do need to be taken urgently to reduce the danger of the spread of this disease:
1) much greater regulation and restrictions on poultry industry and transport; and
2) much greater controls put in place to keep domestic ducks, geese and chickens away from areas where wild waterbirds occur – so that such species do not fall victim to outbreaks.
With very best wishes,
Director, Birds Korea