Good news for endangered turtles

On gender balance

The sex of a baby marine turtle is determined by the egg’s temperature at incubation. The warmer the weather, the more female baby turtles there are. (The phenomenon is called temperature-dependent sex determination.)

Yet, in spite of global warming, researchers studying green turtles in northern Cyprus report that males and females are breeding in nearly equal numbers.

Adulthood

By far, more of the turtles hatched in the area are female, but the gender balance evens out by adulthood. How this happens is a mystery.

“There are a number of theories,” said Lucy Wright, an ecologist at the University of Exeter in England and the lead author of the study, which appears in The Proceedings of the Royal Society B.

“These males may have been produced on beaches somewhere else, or for some reason male turtles survive better than females.”

One male turtle tracked with a satellite travelled to multiple nesting beaches in Cyprus and Turkey and then in North Africa.

Research

The researchers found that in their study area, 28 males produced offspring with 20 females. And males bred with multiple females, improving reproductive success and reducing the threat of inbreeding.

The turtles are endangered, so the findings are encouraging. “It is very good news that they’re able to deal with this very high female-skewed ratio,” Wright said.

“There are other threats that are probably more worrying.”  The biggest threat to marine turtles is being caught in nets intended for fish.