Re: Migration of Whooper Swans and Outbreaks of Highly Pathogenic Avian Influenza H5N1 Virus in Eastern Asia
I've long assumed that much AI transmission wasn't always directly from one species, but rather like the passing of a baton in a relay race. (Dr. Niman's analogy) Even if one species didn't get infected in their breeding area (which is likely as they don't always "mix" much while breeding), their travel companions might be asymptomatic carriers and would pass it to another species (including local wild birds) during a several-day food/rest stop.
I remember when H5N1 first came to Turkey in 2005/2006. It arrived in some migratory birds that died at a reservoir, then about 3 weeks later local wild birds started dying, then another 3 weeks later local poultry started dying, and about 3 weeks later people started dying. I think it takes some time for an infection to spread enough that there is a higher density of ill birds, thereby creating the circumstances for likely spread to other hosts.
If those Whooper Swans are like our local Trumpeter Swans, they claim a lake as their exclusive territory during breeding. Other swans might make quick stops during migration, but once breeding has started an established pair will attack other swans. However, during migration they share lakes/ponds/wetlands with other swans and a wide variety of other species. That mix of species can vary during their migration, as there are major "funnels" where there may be a one time mixing with another species.
Given all the variables in migratory patterns, etc. I'd consider the conclusions from a single-species study to be less reliable than one from a multi-species study.
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...but there are others: Ducks and geese, songbirds and seabirds...They do different things, migrate in different ways, eat and behave differently...
I remember when H5N1 first came to Turkey in 2005/2006. It arrived in some migratory birds that died at a reservoir, then about 3 weeks later local wild birds started dying, then another 3 weeks later local poultry started dying, and about 3 weeks later people started dying. I think it takes some time for an infection to spread enough that there is a higher density of ill birds, thereby creating the circumstances for likely spread to other hosts.
If those Whooper Swans are like our local Trumpeter Swans, they claim a lake as their exclusive territory during breeding. Other swans might make quick stops during migration, but once breeding has started an established pair will attack other swans. However, during migration they share lakes/ponds/wetlands with other swans and a wide variety of other species. That mix of species can vary during their migration, as there are major "funnels" where there may be a one time mixing with another species.
Given all the variables in migratory patterns, etc. I'd consider the conclusions from a single-species study to be less reliable than one from a multi-species study.
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