Researcher thinks vitamin deficiency behind mass bird deaths

11 min

The populations of many bird species, especially ones that spend time in the thousands of tiny islands that skirt the Baltic Sea, have declined drastically in roughly the last decade. Some species have fallen by more than 50 percent. Many researchers suggest a variety of reasons, many manmade, for why bird mortality rates seem to be on the rise. But one researcher thinks he may have found a common chemical culprit, a vitamin B1, or thiamine deficiency.

Lennart Balk, a professor in biochemical toxicology at Stockholm University, says that he has shown thiamine deficiency accounts for birds with symptoms of paralysis, like not being able to hold their wings next to their bodies, convulsions, seizures, eye disorders, anorexia, and general disorientation. One way that he has shown it is by treating sick birds with a shot of vitamin B1. After giving them the shots they were able to fly away, Balk told Radio Sweden.

In 2009 Balk and his team published a paper claiming that many birds had the same thiamine problem that had been established in some species of fish. Since then his studies have indicated that a great variety of species are affected by thiamine deficiency: the herring gull, the eider duck, the starling, swans, and mallards, to name a few.

His research has drawn some sharp criticism. One vocal critic, Martin Green who works at Lund University and who spoke with Radio Sweden in 2011, suggested that Balk's focus is too narrow to explain population decreases. In 2011 he said that the deaths of the eider ducks, for example, could be acccounted for by a range of reasons making for a tougher environment: sickness, global warming, and pollution in the notoriously dirty Baltic Sea.

Other researchers have said there are different reasons, often manmade ones, for high deathrates in different species. For example, the banning of open air garbage dumps has reduced food supply for some birds. Or, the largest number of deaths are limited to species that eat mussels. Or, there are oil spills where migrating birds spend their winters.

But Balk said that he has no cause to dispute that thiamine deficiency could have to do with some nasty chemicals from human activity. And he said his research set out to tie neurological problems in some species to vitamin deficiency, and not necessarily the population declines. But while Balk's research to date may not have solved the mystery of bird deaths, he is convinced he has found a clue. And he said his research team would look to publish findings this fall that suggest the problem is more widespread than just the Baltic region.