Australian scientists have documented a surprising rate of sex change in wild birds, a phenomenon that could be explained by growing pollution or other environmental triggers. A study on five common Australian species, including Kookaburras, Pies and Loricts, revealed that around 6% of birds presented the chromosomes of one sex but the reproductive organs of another.
The results have shown that a surprisingly high number of birds had changed sex after birth, researchers from the University of Sunshine Coast (Australia) said. “This indicates that the determination of sex in wild birds is more fluid than what we thought, and can persist until adulthood,” said Dominique Potvin, co-author of the study, who carried out DNA tests on nearly 500 birds.
More females that have become male than the reverse
The vast majority of sex changes involved genetically female birds developing male gonads. “We also discovered a genetically male kookaburra which was reproducingly active with large follicles and a dilated oviduct, indicating a recent production of eggs,” said Dominique Potvin.
The change of sex is known in certain species of reptiles and fish, but it is believed that it remains rare in birds and mammals. Scientists had already documented sex changes in frogs induced by pollutants or higher temperatures. But the cause of sex changes in wild birds is not yet clear, indicates the report of the University of Sunshine Coast.
The phenomenon could be due to environmental factors, such as the accumulation of hormonal disturbing chemicals in wild areas. “Understanding how and why the change of sex occurs is vital for conservation and to improve the precision of research on birds,” added Dominique Potvin. The study was published this week in the scientific journal with Biology Letters Reading Committee.