chernobyl and birds, 20 years later

April 26, 2006

in Science

Today is the 20th anniversary of the nuclear disaster in Chernobyl. National Geographic had a nice overview article in their April issue. Human impacts have been documented, but what about the impact on wildlife? Some reports have portrayed the huge exclusion zone as something of a park, teeming with wildlife.  In fact, few if any studies have been done evaluating the effects of the disaster on population densities of common plants or animals [1].

Some of the most extensive studies have been done on Barn Swallows (Hirundo rustica).  Some findings include:

  • At Chernobyl, Barn Swallows have a tenfold increase in albinisim, usually in the plumage of the head. It is persisting, and the similarity in the albinism of parents and their chicks indicates it is a germline mutation [1,2].
  • Albinism is associated with smaller body size.
  • There has been a fivefold increase in the asymmetry of the long tail feathers.

These mutations may seem insignificant, but that’s not the case. The albinism is due to a reduction in carotenoid pigments, which are important in the coloration of feathers.  Carotenoids are not only feather pigments, they are antioxidants that enhance the immune system.  Albinistic/small bodied Barn Swallows had decreased survivorship, likely due to a reduction in the free radical scavenging function of the carotenoids. Survivorship has decreased 24% for males and 57% for females.

Tail length and symmetry are also important to Barn Swallows. Long-tailed males with symmetrical tails are most appealing to females.  The tail feathers serve as status signals, indicating prime health, and these males are most successful in mating. Barn Swallows may have an increased need for antioxidants at Chernobyl, leaving little left for development of plumage signals.

Other findings:

  • There is a high level of sperm mutation in Chernobyl Barn Swallows. [3]
  • There are many non-breeding birds in the population, 23% versus nearly zero at control sites. Radiation has somehow caused the birds to lose their motivation to breed. [4]
  • For birds that do breed, reproductive success is lower, with reduced clutch size and hatching success. [4]

Barn Swallows breeding at Chernobyl are migratory, wintering in Africa. While there is site fidelity in Barn Swallows and other species, the authors of the Barn Swallow studies note,

“Mutations with slightly negative fitness effects could easily be exported out of the contaminated areas via organism migration, with consequences for populations that have not been directly exposed to radiation from the disaster.”

What about other birds?  This web site discusses increased radioactivity in European Robins (Erithacus rubecula) collected in The Netherlands, presumably having migrated through the fallout area, after the accident. A paper that examined reproductive success of a variety of birds on the west coast of the U.S. discussed a mysterious, widespread breeding failure in over 40 species of birds in northern California in 1986 that coincided with the passage of the radioactive cloud from Chernobyl.  While there was no direct evidence that the radioactivity was the cause of the failure, the circumstantial evidence was both interesting and compelling [5].

As the world is faced with a real and pressing need for alternative energy, the long-lasting impacts of the Chernobyl accident give us pause when considering nuclear power. I believe that in the last twenty years, we’ve developed better and safer technology for nuclear power plants. It may well be that the risk of an accident is far less than the sure risks of continuing to use fossil fuels. A big sticking point for me is our continued inability to figure out what to do with spent nuclear fuel.  Our energy gluttony has led us down many sad roads.  I can only hope we don’t travel down this one ever again.

[1] Møller A. P. and T. A. Mousseau.  2006.  Biological consequences of Chernobyl: 20 years on.  Trends in Ecology and Evolution 21: 200-207.

[2] Møller A. P. and T. A. Mousseau. 2001. Albinism and phenotype of barn swallows (Hirundo rustica) from Chernobyl. Evolution 55:2097-2104.

[3] Møller A. P., P. Surai, and T. A. Mousseau. 2005. Antioxidants, radiation, and mutation as revealed by sperm abnormality in barn swallows from Chernobyl. Proc. of Royal Society B 272:247-252.

[4] Møller, A. P., T. A. Mousseau, G. Milinevsky, A. Peklo, E. Pysanets and T. Szép. 2005. Condition, reproduction and survival of barn swallows from Chernobyl. Journal of Animal Ecology 74: 1102-1111.

[5] DeSante, D.F. and G. R. Guepel.  1987. Landbird productivity in central coastal California: the relationship to annual rainfall, and a reproductive failure in 1986.  Condor 89:636-653.

New paper: Møller, A. P., T. A. Mousseau, F. de Lope, and N. Saino. 2007.  Elevated frequency of abnormalities in barn swallows from Chernobyl. Biology Letters 3:414-417. (abstract)

Clare April 26, 2006 at 3:07 pm

On the plus side, the ability to glow in the dark has greatly enhanced their foraging after sunset.

Cindy April 26, 2006 at 8:58 pm

hey, I know that bird 😉 interesting post- totally unrelated somewhat, but I recently discovered my thyroid is completely out of whack.. and while doing some research on this condition I read where the victims of chernobyl basically had their thyroid glands, among many others, destroyed. A wide reaching tragedy. I too hope that is a road we never travel again…

Rob Miller April 26, 2006 at 10:50 pm

Thanks for the story. Unfortunately we need reminders like this of the damage that humans have caused to the planet. On a partially optimistic side, I wonder if the mate selection and not breeding will allow nature to work through this. If sick birds don't breed, either due to lack of interest or lack of a mate, then there will be fewer sick offspring. Of course, there must be enough healthy birds left to propegate the species. Any thoughts?

Nuthatch April 27, 2006 at 6:01 am

You're right, Rob — the small-bodied birds (often also short/asymmetrically-tailed, pale) are selected against, and the numbers of them don't increase in the population. Unfortunately, the radiation damage is ongoing, and the population is sustained by immigrants from outside the exclusion area, which are exposed to the radiation. There are copies of a lot of the swallow papers at Mousseau and Moller's web site for more info.

Rob Miller April 27, 2006 at 12:27 pm

Yes, good clarification. The ongoing contamination would continue to cause problems. I guess my sense of hope overcame this details. Thanks again for the engaging topic and dialog.

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