Migration of waterfowl in E Asian Flyway & spatial relationship to H5N1

Migration of waterfowl in E Asian Flyway & spatial relationship to H5N1  

HPAI outbreaks along the East Asian flyway are related to latitude and poultry density, not to core migration corridor or wetland habitats

01 April 2010 – A recently published study that uses a newly developed Brownian bridge spatial analysis methodology found that highly pathogenic avian influenza (H5N1 HPAI) outbreaks reported along the East Asian flyway were related to latitude and poultry density but not to the core migration corridor or to wetland habitats used by migratory waterfowl. These findings suggest that there are temporal mismatches between the timing of reported outbreaks and wild duck movements.

Given that the Guangdong province in China has been pinpointed as the epicentre of H5N1 HPAI, it was deemed critical to better understand disease transmission dynamics between wild and domestic birds in this area. Poyang Lake is the largest freshwater body in China and it lies within the East Asian flyway. This lake is situated near Guangdong and represents a migratory corridor as well as a significant congregation site for waterfowl. Herein there are surrounding rice fields and free-grazing poultry flocks that interact with wild waterfowl, a situation that has been said to be largely conducive to avian influenza transmission across the poultry-wildlife sectors.

Scattered yet recurrent reports of H5N1 HPAI in healthy wild ducks at Poyang Lake, Qinghai Lake, and other locations globally, have raised concerns about the potential of resilient free-ranging wild birds to disseminate the virus over short and long distances. However, the lack of information about the migratory ecology of wild ducks has hindered understanding of the role these birds play in connecting regions that host and report H5N1 HPAI outbreaks throughout Asia.

In view of this information deficit, during 2007 and 2008, a group of research scientist from different countries mounted satellite transmitters on wild ducks at Poyang Lake to examine the location and timing of spring migration and to identify any spatiotemporal relationship with H5N1 HPAI outbreaks reported in this area.

The study included wild duck species such as the Eurasian wigeon (Anas penelope), the northern pintail (Anas acuta), the common teal (Anas crecca), the falcated teal (Anas falcata), the Baikal teal (Anas formosa), the garganey (Anas querquedula), the mallard duck (Anas platyrhynchos), and the Chinese spotbill (Anas poecilohyncha), a group of waterfowl that could play a role in transmission, based on their ability to serve, in general, as reservoirs of low pathogenic avian influenza viruses .

Satellite signal-based tracking maps indicate that these wild ducks [excluding the last two species] followed the East Asian flyway along the Chinese East coast to breeding areas in Northern China, Eastern Mongolia, and Eastern Russia yet none migrated West toward Qinghai Lake [the site of the largest wild bird epizootic], thus failing to demonstrate any relevant migratory connection to the Central Asian flyway.

Data analyses used novel approaches to integrate ecological information to better inform epidemiological investigations seeking to explain, predict and understand the spread of avian influenza viruses. The Emergency Centre for Transboundary Animal Diseases (ECTAD) at the UN Food and Agriculture Organization (FAO) will continue to actively collaborate with national governments, research centres, diagnostic laboratories, and universities to further elucidate the dynamic evolution of transboundary diseases in diverse ecological landscapes that include wildlife, livestock and people.


This is excellent. It seems to me that this provides HKBWS and WWF with further evidence that wild birds are not implicated in transmission of H5N1. Consequently, closing Mai Po NR serves no useful purpose.

I would urge the two organisations to get together and request Government to review this ridiculous measure, which has no basis in science.

We need to step up the pressure.


[ Last edited by cgeoff at 12/04/2010 21:39 ]


Dear all

March and April are migratory months and the Barn Swallow killed by Avian-flu cannot be related to
chick-farms in the colony. The dead bird itself was probably infected while quite a long way from
Hong Kong. On the other hand, a spontaneous outbreak resulting in deaths in local chick-farm(s)
and even one single wild bird could have established much stronger evidence in the relation between domestic birds and wild birds and the subsequent shutdown of MPNR would be more convincing.

In the present circumstances, there are obvious irrational feelings rather than rational decision based on probability of evidence and therefore unacceptable. AFCD is now seen, with regard to this particular incidence, as a highly bureacratic body trying their best to find the easiest way out to avoid the remotest chance of public outcry.

S L Tai


While March and April are, indeed, months of spring migration, Barn Swallow breeding activity in HK can begin as early as mid January in warm years. So, without having examined the bird, it is not possible to say whether it was on passage, or is a locally-breeding bird.



As I understand it, the closure of Mai Po is not related to the risk of wild birds carrying H5N1 over long distances (as discussed in this paper). This has always been a controversial topic, and it is interesting to see the latest evidence.  Closure of the reserve is related to the risk of people contracting H5N1 from wild birds. There is absolutely no evidence that this has ever occurred anywhere in the world. The closure of Mai Po is therefore based on NO EVIDENCE WHATSOEVER. It is a knee-jerk reaction by government to give the impression that they are doing something to "protect" the HK population.

Personally, I think a far more appropriate response would be to post details of the case at the entrance to Mai Po and let visitors decide whether to take the risk of entering the reserve. If an individual is worried about catching H5N1, they need not visit Mai Po, there is no need to penalise those of us who have made an informed decision that Mai Po is safe. Closure of the reserve also gives the impression to the public that the true risk to people comes from wild birds (again, there is no evidence to back this up), which could have significant implications for conservation.

In this particular case, the closure of Mai Po seems really ridiculous given that the speices affected is commoner outside the reserve, and is certainly in closer contact with people while breeding in nearby villages!


John is, of course, right to define the problem more clearly than I expressed. However, the paper referred to does go a long way to dispelling the notion that wild birds are the risk vectors for H5N1 as far as people are concerned.

What I find slightly frustrating is that the Society does not appear to be applying pressure on this issue.

Are we a pressure group (when needed), or just a friendly society (to borrow and rather outdated English expression)?



Dear all

The basic factors are, I think, have been laid before the forum. To be a responsible government body,
AFCD should take precautionary measures by steps. HK parents are, in my opinion, on average over-protective of their children. To dispell their fear, the initial step might be stopping of all
guided tours for schools. Next could be to limit the age or no. of visitors daily, say over 21 years old
and 200 respectively.

The above suggestions are by no means science-based. But they align to the present political and
military policy of a superpower state that they will not resort to nuclear weapons when they  
first suffer armed attack of any kind. In a word, AFCD should review their present policy and decision making mechanism as regards birdflu happening in HK. The present one is just like death sentence
for all criminal offences, be it spitting in the street or murder of the first order.

I do hope WWFHK and HKBWS management people are reading our discussion and take up necessary steps.

I look forward to reading what comments Bena and Dr Cheung Ho Fai would make and action they intend
to take.

S L Tai


Dead ducks indeed don't fly

Back in around late 2004, I showed that bird flu outbreaks blamed on wild birds simply did not fit the pattern of bird migrations - including timings of migrations.
Dead Ducks Don't Fly

Since been extremely active in trying to show it's just wrong-headed to blame wild birds as major vectors for H5N1 spread.
FAO has been pre-eminent in blaming wild birds; so this latest report is a welcome change, but too late - till now, just politics and big business (and industrial poultry farming indeed big business) that has shaped the debate, and policy.
Conservation groups have been way too weak on the issue; some have taken money from FAO etc, surely muting their comments. One of more ridiculous "studies" I've seen involved someone in US banding yellow-billed magpies, ostensibly to check re H5N1 migration.
- yet how much effort have anyone noticed regarding studies of poultry trade, including smuggling? FAO very very very quiet regarding this; but, sadly, so too conservation organisations. It matters, I believe; even read of wild birds being scared/killed in Russia due to flu fears.
Like an old-fashioned witch hunt: just as much unreason behind it.

Hong Kong evidently started the blaming wild birds notions: with Penfold Park outbreaks (migratory birds blamed, yet evidence scant; egrets there likely resident anyway). These notions should have been rebutted from the outset; just based on arm waving, and an easy option.

Bird Watching Society has, in my view, been far too passive re this issue.
To me, as anyone who's visited my forum on wild birds and flu has seen, it's important: I believe it's crap that kids should be scared of wild birds. Just adds to ecophobia/biophobia in Hong Kong - in turn weakening conservation, facilitating yet more concreting of our environment.
Surely Bird Watching Society could have done more, still can do more, to stand up for wild birds.

Yes, Mai Po closures surely about being seen to take action. Showing poultry industry folk they're not being solely targeted.

[ Last edited by wmartin at 7/05/2010 16:39 ]


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Hong Kong Outdoors enjoying and protecting wild Hong Kong. DocMartin includes H5N1 and wild birds info


HK Govt mindset re H5N1 and wild birds

Here's correspondence I had with food and hygiene dept, in spring 2008. Gives some idea of government mindset regarding closures (and their lack of any science underpinning the closures, but never mind about that...)
Dear Dr York Chow:

Here's a post I've just made to HKBWS forum:

The witch hunt vs wild birds has eased, but is clearly not over.

Hong Kong was the first place to blame wild birds for spread of H5N1
(poultry flu variant); and not gonna stop blaming wild birds no matter
the evidence.

Here's a bureaucratic, knee-jerk reaction, driven not by science by by
paper pushers who likely barely leave the office (anyone ordering Mai
Po closures ever walked around the reserve at such times, ever noticed
that - as yet - not one case of H5N1 poultry flu at the reserve?).
Dear Dr York Chow:

Here's a post I've just made to HKBWS forum:

The witch hunt vs wild birds has eased, but is clearly not over.

Hong Kong was the first place to blame wild birds for spread of H5N1
(poultry flu variant); and not gonna stop blaming wild birds no matter
the evidence.

Here's a bureaucratic, knee-jerk reaction, driven not by science by by
paper pushers who likely barely leave the office (anyone ordering Mai
Po closures ever walked around the reserve at such times, ever noticed
that - as yet - not one case of H5N1 poultry flu at the reserve?).

I've protested before, long railed against blaming wild birds for being
major vectors of H5N1 poultry flu. But what's the use; logic and
commonsense go out the window when a witch hunt is in progress.

- for far more info on wild birds and H5N1, see my blog/forum at: ... nd-migratory-birds/

Yours sincerely,
Dr Martin Williams
Dear Dr. Williams,

Thank  you  for  your  email  to  the Secretary for Food and Health
dated 6
February, 2008 expressing your view on the closure of Mai Po Nature
(MPNR) after a dead bird collected around MPNR tested positive against

While  we  appreciate the inconvenience caused to you by the closure
of the
MNPR,  we are of the view that the closure is necessary in order to
public  health.   We  introduced the guideline in 2006 to temporarily
the outdoor sections of government owned / managed facilities where a
number  of  wild  birds  congregates  (eg.  MPNR, Wetland park) and
aviaries  in  recreational  parks  for  3  weeks when a dead bird
within  3  km from these facilities as a precautionary measure to
public   health.    It   was   formulated   having   regard  to  the
epidemiological  picture  of Highly Pathogenic Avian Influenza (HPAI)
in  wild  birds  at  that  time  (15  wild birds and 2 stray chickens
infected  with  H5N1 virus) and the fact that HPAI virus can be
from  wild  birds  to  humans  directly  or indirectly through

The guideline aims at reducing public contact with possibly
materials from wild birds only.  Indoor activities in affected
such as the Education Centre of the MPNR and the indoor section of the
Wetland Park remain accessible to public, subject to the
implementation of
specific biosecurity measures to prevent contaminated materials, which
carry HPAI virus, from being brought into such areas.

The Agriculture, Fisheries and Conversation Department (AFCD) had met
representatives of the World Wildlife Fund Hong Kong (WWFHK) and the
Kong Bird Watching Society (HKBWS) in July 2006.  It was agreed at the
meeting that WWFHK’s employees working on the management / maintenance/
research work and specialist groups such as the HKBWS engaged in
of birds and scientific research activities would be allowed to enter
closed area provided that they maintain proper hygiene in the MPNR and
appropriate bio-security measures while working in the wild bird
congregation area there.

As there has not been any new case of birds found infected with avian
influenza virus near the Nature Reserve in the past 21 days, the Nature
Reserve has been re-opened to the public on 27 Feb 2008.

Yours sincerely,

Joyce Kok
for Secretary for Food and Health
Hi Joyce:

"HPAI virus can be transmitted from  wild  birds  to  humans  directly
or indirectly through contaminated

- any evidence for this.



thought not

Dear Dr. Williams,

Thank you for your two emails dated 10 March 2008 and thanks again for your
concern on the control of avian influenza measures.

The  H5N1 virus we isolated from wild birds in Hong Kong has so far proved
to be highly pathogenic avian influenza virus which can be lethal. As we
could not ignore the possibility that the virus could be transmitted from
wild birds to humans directly or indirectly through contaminated materials,
it would be necessary for the administration to introduce measures to
reduce such risk.

We are sorry for any inconvenience caused to you during the closure of Mai
Po Nature Reserve.

Yours sincerely,
Joyce Kok
Dear Joyce:

Thank you for your email, in which you support my belief there is no scientific basis for closing Mai Po because a dead bird or two with H5N1 has been found nearby.

"we could not ignore the possibility that the virus could be transmitted from wild birds to humans directly or indirectly through contaminated materials"
- this is vague and woolly minded. Not remotely scientific.

As is clear from evidence worldwide, the H5N1 variant of concern is primarily a poultry disease. And whilst the administration has done much to reduce the incidence in local poultry, and associated markets (such as the bird market), we have not lately seen such draconian measures as closure taken recently.

As you should be aware, no wild bird species is known to be capable of surviving, sustaining and spreading H5N1 poultry flu.
It is highly lethal to wild birds, so an infected bird soon sickens, and dies, swiftly ending a potential chain of transmission.

Despite extensive testing, not one apparently healthy wild bird has tested positive for H5N1 poultry flu in Hong Kong.
The dead wild (and "wild" - for some individuals surely or probably from captivity) birds found in Hong Kong that tested positive for h5n1 have been from scattered locations. Despite the bird concentrations at Mai Po, and surveillance there, is it just one case from Mai Po over the years? - in turn, suggesting H5N1 is rare in wild birds, but overwhelmingly outside the reserve.
You might wish to consider just how and where these birds may have contracted the virus - scavenging dead, dumped poultry (smuggled in, so with chance of h5n1), or infected songbirds from captivity?

Especially with birdwatching not involving contact with wild birds, and no case worldwide (that I'm aware of) of a person thought to have contracted h5n1 from a wild bird, there is and was no discernible risk to Mai Po visitors.

Thus, knee-jerk reaction would indeed seem an appropriate description for the Mai Po closures.


Yours sincerely,
Dr Martin Williams
(silence... .... ...)
Clearly, then, science alone won't win this "debate". Need something else; but who knows what that may be? Public opinion would do the trick, if could muster enough support for wild birds.

[ Last edited by wmartin at 7/05/2010 17:23 ]
Hong Kong Outdoors enjoying and protecting wild Hong Kong. DocMartin includes H5N1 and wild birds info