Zebra finches go mad with mercury, and other animal updates

PRINCETON, N.J. — I spent this week at the Animal Behavior Society meeting at Princeton University, which, when you’re an animal blogger, is something like releasing a kid in a candy store. Seven-hundred-and-fifty scientists from around the world had gathered to give each other updates on all creatures great and small, marine and terrestrial and airborne. Here are a few things I learned:

Mercury may make birds mad as a hatter

The liquid metal mercury is toxic, even in small doses. In humans, large doses cause lethargy and depression. Smaller amounts result in dementia. But what does low-dose mercury poisoning do to a bird? John P. Swaddle of the College of William and Mary and colleagues exposed zebra finches to an amount of mercury consistent with a contaminated environment. Poisoned birds were bolder and hyperactive, but they were also lower in rank and spent less time feeding than birds that had not been exposed to the metal. With the birds displaying no signs of depression, hyperactivity would put them more on the dementia side of mercury poisoning, Swaddle said during his August 11 presentation. And that, he noted, could lead to an increased risk of predation.

The guys that walk all over the girls

Researchers have spotted an odd behavior among ornate spiny-tailed lizards in the Eilat Mountains of Israel: A male will flip a female on her back and walk back and forth over her, Amos Bouskila of Ben-Gurion University of the Negev in Israel reported on August 13. Sometimes a female would object to the behavior and fling the male off her. Other times, the female would voluntarily turn onto her back, inviting the guy to walk all over her. Bouskila said that he and his colleagues aren’t quite sure what the lizards are doing. The action does not resemble fighting or copulation, and it always involves one male and one female. It’s possible that the behavior has a role in mating among some of the endangered lizards, Bouskila said. The males might be marking the females with chemicals from their femoral pores, he speculated. Or the activity might somehow help females evaluate males, or it could help to strengthen a bond between this long-lived lizards.

Ocean acidification may affect fish schooling

More than half of the world’s fish live in a school at some point in their lives, so that makes schooling an important behavior to understand, Lauren Nadler of Australia’s James Cook University said on August 13. Nadler, studying tropical damselfish (Chromis viridis) in the lab, tested what would happen to small schools under attack when those groups were comprised of fish familiar and unfamiliar with each other. When there was a disturbance (simulating a predator’s arrival), schools of familiar fish responded more quickly, and they covered more ground than the groups of unfamiliar fish. That may make them more likely to survive a predator attack, Nadler said. But when she and her colleagues acclimated the damselfish to waters with higher levels of carbon dioxide, they lost their preference for schooling with familiar fish. So as carbon dioxide levels rise and the ocean becomes more acidic, fish schooling behavior could change, Nadler said.