Bird Brains Tell Tale of Radiation Damage

Bird Brains Tell Tale of Radiation Damage
USC Researchers Study Flora and Fauna around Chernobyl

You can learn a lot from a bird brain — especially if that bird brain spends half the year nesting in the forests and abandoned farmlands surrounding Chernobyl.

For the past several years, USC biology professor Timothy Mousseau and his colleague Anders Møller have been doing just that: studying migratory and non-migratory birds (plus a wide range of insect and plant species) across swaths of the Ukraine and Belarus affected by the 1986 nuclear disaster in an effort to better understand the effects of low-dose radioactive contaminants on living organisms, including humans.

And what Mousseau and Møller have found so far is less than encouraging, as their research contradicts some of the more optimistic findings that have circulated through the mainstream media in recent years.

“We’ve had this ongoing feud with some members of the biological community who have studied in Chernobyl,” Mousseau says. “They’ve given us a really hard time in the media over our findings, but they base their argument, really, on no data. They’ve made suggestions that mammal populations are thriving, that it’s this Eden, that there’s this wildlife refuge that is overflowing with large animals in the same way that you might find at Yellowstone or other refuges, and that is so far from the truth.”

“They make these proclamations purely on the basis of anecdotal observations,” he adds.

“‘Well, we saw a moose!’ or ‘We saw a wild boar!’ or, ‘We saw a bird’ — one bird — ‘in this
contaminated area, so it must be OK.’”

According to Mousseau, however, insect, reptile and amphibian abundances are dramatically reduced across the region, and fruit trees in the more radioactive areas frequently fail to bear fruit, likely because there are so few bees present to pollinate them.

And when it comes to birds — which Mousseau describes as “a really good model organism” because they’re biologically similar to humans in many respects, as well as relatively easy to catch and identify — species richness is down 50 percent and overall abundance is down more than 60 percent, while abnormalities among the birds that are present are fairly common.

After trapping 550 birds and approximately 50 species last summer, Mousseau’s team also discovered that the average head size of birds in the region, which correlates pretty closely to the size of their brains, is down at least 5 percent, which Mousseau describes as “huge for a bird.”

“And the more contaminated the area, the worse the effect was,” says Mousseau.

“What was even more interesting, and what gives the study a lot of weight, is the fact that the effect is much more pronounced with young birds,” Mousseau adds. “By the time the birds are a little bit older, the effect is still there but it’s reduced. What that tells us is that birds with small brains are not surviving.”

The effects are also more heavily pronounced in migratory birds, like barn swallows, than in birds that live year-round in the contaminated zone. The hypothesis is that during long distance migration these birds (which are philopatric, meaning they return to the same nests year after year) use up the antioxidants stored in their bodies, then immediately gorge on contaminated food and repair their nests with contaminated mud at a time when they are most susceptible to disease. As a consequence, birds like the barn swallow, which Mousseau describes as “very sensitive,” have become almost extinct in the region.

“We see this same thing in humans,” Mousseau says. “You may be susceptible to a disease but you don’t express it because you’re living in a happy, healthy environment… It’s the interaction of factors that really leads to the expression of these negative effects.”

In fact, if there’s any silver lining to be found at Chernobyl, it’s that the vast contaminated area provides researchers a sort of “natural laboratory” for the study of low-dose radioactivity and its effects on various organisms. And while Mousseau stresses that so far the ongoing nuclear catastrophe at Japan’s Fukushima power plant is very different — in part because fewer types of contaminants have been released into the environment than at Chernobyl — Mousseau urges the scientific community to begin collecting useful data there, too, and as quickly as possible.

“I think the first thing we’ve learned from Chernobyl is that 25 years later, as we’re trying to disentangle and unravel the story, we see signals, we see cancers, we see other types of morbidity, but we don’t have enough information to really nail it down, especially for the human side. With Fukushima we should be planning to get a bunch of data collected right away so that we know exactly how much stuff is there now, so that we can track how it moves in the future.”

“It’s still winter there, so plants haven’t bloomed, a lot of the birds haven’t shown up again — yet,” he adds. “So there’s still time to actually get over there and catch those things as they come in. We need to get a baseline sample and then see what the heck happens in the coming years.”