Thursday, July 12, 2007

Brightly Colored Birds More Affected By Chernobyl

On ScienceDaily today, a really fascinating report on how the Chernobyl meltdown has affected some bird species more than others. They studied 57 species, and found that those that have had the most drastic declines since the disaster fall into four groups:

1. Species that depend upon dietary carotenoids for their red, yellow, or orange plumage (orioles, blackbirds, blue tits, for example).
2. Species with relatively large eggs.
3. Species that migrate.
4. Species with wide dispersal patterns.

Apparently all of those groups have lifestyles that place a high demand on antioxidants (for plumage coloration, flight energetics, etc). The study suggests that high levels of radiation have a disproportionately negative impact on species that require lots of antioxidant compounds. Radiation levels in a normal (ie not post-meltdown) environment vary due to natural things like differences in isotopes between different geological features, and the researchers suggest that these new discoveries can be used to make predictions about species success in places where radiation levels can be quantified.

It is important to realize, from the data in their report, that some of the species studied fall into more than one of the high-risk groups: for example, orioles depend on carotenoids for their yellow plumage (see image above), and also migrate long distances.

Also, another thing I gathered from the report that I thought warranted a note: bird species that are taxonomically close might not be impacted to the same degree as less-related species with similar lifestyles (meaning, you can't necessarily predict the impact on a species by looking at stats on a sister species). For example, in the family Paridae, blue tits, which are highly dependent on carotenoids, have faced much sharper declines than coal tits.

I've always been fascinated with the Chernobyl meltdown (it's one of the landmark events in the year I was born, btw) and its impacts on the local wildlife. Despite my unabashed mammal and dino bias as far as interests go, the radiation-eating fungus recently discovered there is still definitely my favorite science story of 2007 (see my blog post on it here). One thing that is both interesting and sad is that some reports have shown that wildlife has actually benefited, in some ways, from the catastrophe, since human activities in the area have effectively ceased.

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