Male starlings that ate tainted worms suffered brain damage but produced a more attractive mating call.
Scientists recently found that starlings that ingested estrogen-tainted earthworms became brain damaged, and paradoxically, were more attractive to females. The affected male starling produced a far more complex mating song, according to a recent article published by the Public Library of Science.
Because female starlings choose mates based on the complexity of a male’s song and with their singing ability, the affected starlings are breeding more. The downside is the chemicals weaken the starlings’ immune systems and cause other anatomical and behavioral issues.
The affected birds are more likely to reproduce sick offspring and the researchers could not predict how this would affect the already declining wild population of starlings in the coming years.