In a paper in the Journal of Analytical Atomic Spectrometry [JAAS] (in case you haven't read your latest issue), I learned that bird migration patterns in Europe are still kind of hazy, despite the long standing and often intense interest on the part of birders and conservationists. It's just not an easy problem. Not being a birder myself, I didn't know this, nor did I have much interest in migratory patters of birds prior to bird flu. Now many of us have a newfound interest in it. Which is why a new method to figure out migratory bird patterns caught my eye.
The usual methods are both labor and resource intensive. You can band the birds and do a capture - recapture statistical analysis, or try putting little transmitters on them or even do a complete census of migratory stop-over areas. A recent idea is to use chemical analyses to indicate a geographic origin, but the more common elements (carbon, hydrogen, etc.) haven't been very precise, geographically, and use of trace elements frequently required invasive techniques, for example, bone samples. One of the more interesting trace elements is strontium, which often takes the place of calcium in bone and is also potentially informative about the location where a bird spent time because it also reflects geochemistry. For all the chemical analyses, it's not the amount of strontium itself, but the ratio of stable isotopes, in the case of strontium, the isotopes strontium-87 and strontium-86.
What's an isotope? The word comes from the Greek iso- for "the same" and topos, for "place." Chemical isotopes are chemical species that are "in the same place." The location referred to is the same place in the periodic table of the elements. Different isotopes of the same chemical species (atoms of the same element) have the same chemistry, which is what their location in the periodic table says, but differ in another way, their atomic weight. By examining the ratio of the number of atoms of strontium of two different atomic weights, weights 87 and 86, information is gained on the geochemistry of the location where the bird spent time.
Having to use bird bone is not ideal. Bird feathers would be better. And that's what the paper by Font et al. in JAAS did -- measure the strontium isotope ratios in the feathers of a bird species, the Sedge Warbler. There isn't a lot of strontium in the feathers of a bird, although what there is seems to reflect the location where the bird was when it grew its feathers. Using highly sensitive analytical techniques (hence the description of the method in a specialized analytical chemistry journal), the authors were able distinguish birds from different locations. But there seems to be a long way to go before this method would be practical and well enough specified to be useful (see the discussion section of the paper).
The many obstacles notwithstanding, the autor naturally has high hopes for her method:
"By determining migration pathways, the arrival of potential vectors of diseases from infected areas can be anticipated," said Font. "Knowledge of migratory routes also helps evaluate the likelihood that individual avian influenza outbreaks could be related to migratory bird movements rather than anthropogenic activities, such as poultry movements, which are believed to be the main vector of avian influenza in most outbreaks," she added. (Royal Society of Chemistry news release)
It would be nice. Maybe someday. What this demonstrates, I think, is that Necessity is the Mother of Invention. We know too well that not all of Necessity's offspring grow up to be productive members of society. This one seems still to be in pre-school.
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Interesting. The trouble is, of course, migration routes are not 'highways' that, once built, are reliably travelled over forever. Annual variations in climate can effect where birds go, and how they get there, as we have already seen. And with climate change we can expect new patterns to emerge pretty much unpredictably. This is why I am wary of the the surety some researchers feel about transmission of the Qinghai strain through migratory patterns. You can just about take any two points on the globe and connect them through bird migration--but as the recent Alaska data show, one has to be cautious about the conclusions.
Wild birds have always been a reservoir for influenza. The mystery is not so much how it spreads (and spread it will, no matter what) as it is why low-pathongenic strains transform into HPAI in domestic poultry. In other words, it is probably more a question of local ecology.
Help show it's bird migration rather than humans trying to hide, eat, or sell, infected poultry (or other mammals)?
Did a little birdie give her that idea, or, the funding? Sounds like a limb the poultry industry would be out on (sawing away betwixt themselves and the trunk).
"Interesting. The trouble is, of course, migration routes are not 'highways' that, once built, are reliably travelled over forever. Annual variations in climate can effect where birds go, and how they get there, as we have already seen. And with climate change we can expect new patterns to emerge pretty much unpredictably. This is why I am wary of the the surety some researchers feel about transmission of the Qinghai strain through migratory patterns. You can just about take any two points on the globe and connect them through bird migration--but as the recent Alaska data show, one has to be cautious about the conclusions."
I have to agree with you, Ron. In part at least. The recent research from Alaska revealed that the population density of waterfowl in the tundra region was not sufficient to sustain a chain of transmission of the virus. But, it also revealed an underlying assumption on the part of researchers which is that the tundra is where the transmission occurs. The authors did note that the population density is much greater in the arboreal region to the south, and that 99,000 waterfowl are killed by hunters every year.
Instead of questioning their basic assumption, they concluded that viral spread from Siberia is highly unlikely. Perhaps they should have concluded they were looking in the wrong place. Perhaps they should have asked the local hunters where the birds were to be found?
We have a small pond in our front yard and every year we get a new type of water bird landing in it for a breather on the way up or down the continent. This year the newbie was a ring necked duck. In the past we have had eider ducks (!!!), black ducks, buffleheads, and one year a couple of sandhill cranes.
I know that one especially bad winter about 5 years ago, the migration routes for the sandhills was right over our house instead of over Indianapolis (we are south east of Indy).
I really don't see how marking the birds with anything would help since you won't know where they are going to be from day to day. A blast of cold air or a warm pocket might cause them to alter their routes by hundreds of miles. Even hummingbirds don't use the same ways to get back up here every year and they arrive at different times depending on the weather coming up from the Gulf of Mexico.
I am no ornithologist but dont most of the feathers form while the bird is a fledgling (or do they grow contiuously, like human hair, so samles along the length of the quill would act like a travalogue?). If so wouldn't the strontium isotope proportions relate to the area in which the egg hatched rather than show where it temporarily alighted during its migration. I also thought that long range migratory birds tended to fatten up before the journey and only make short pit-stops enroute.
JJ: I linked to the paper, which is a free download. My reading of it was that the feathers reflect the place where the bird was when the feathers are being formed and that feathers, being keratin based, are constantly being formed and growing, but maybe a birder out there knows the scoop. We do mercury analyses along the hair shaft in human studies, but my understanding of the paper was the the amount of strontium along the feather vane was so small it wouldn't be possible to do this for feathers. Maybe someone else can also read the paper and give their interpretation?
Feathers grow all the time and then fall out during a molt. Some fall out faster and some times they fall out a LOT at a time (you get some weird looking bald birds that way!)
Bird feathers molt twice a year. Once for spring mating and another time for winter. That's why male gold finches are only bright yellow in spring, summer, and part of fall. The rest of the year they look like the female gold finches, pretty dull yet still interesting.
The hivemind comes through, once again. Thanks, G.
The backyard chicken farmer is over here tearing her hair. I would have replied sooner, but I misunderstood the question: I thought that everyone knew that birds molt.
Susan: LOL. I knew that cockroaches molted. I guess that says something about me, huh? City boy.
Feel free to stop over to my blog and read about living with chickens.
I had my own migration route as a kid. Every day I sat in the same bus seat for the same hour-long ride to school. I checked out the same crops and wildlife in same fields and creeks every day for the six years of high school. In seventh grade (1969) it was the last of the DDT residue years, and large birds of any sort were rare. Canada geese populations grew stronger every year, and soon they learned to move through fast in the fall (hunting season) but linger in the spring to get fat on the corn the combine had missed.
One morning I caught a glimpse of a great blue heron fishing a hole in the ice of a small stream. I had never seen a bird that tall, and I had no idea they were native to my home. I couldn't have been more surprised to see a dinosaur.
Humans, messing with habitats, spraying chemicals, changing climates, both global and local, have kept bird migrations in a state of flux for a 3 or 4 human generations. With the news we've seen lately, it seems that someone ought to do a study of the migration of poultry carcasses in trucks and freighters. I think we'd be amazed.
Susan Och wrote, in her own blog, a year ago, "One wonders if the clue to flu resistance in poultry lies in that small sliver of surviving birds, the ones that are being culled with the rest."
Nobody would buy the frankenbirds if resistant birds were bred the traditional way.