High rate of hormones is a weapon to kill siblings

The Nazca dove - a seabird that lives on the Galápagos Island - came out ready to kill its siblings when it was removed. Biologists at Wake Forest University and colleagues have found a link between this killing behavior and high testosterone rates as well as the rate of other male hormones in newly hatched birds.

The research was published online in the June 18 issue of PLoS ONE.

According to biology professor David J. Anderson of Wake Forest University and project director, the high rate of male hormones (also called androgens) increases aggressiveness in young birds whether male or female makes them available. ready to fight to death as soon as it has just hatched.

Many field studies were completed by Martina Müller when she was a graduate student at Wake Forest University.

Anderson said: 'The two Nazca ducks hatched before fighting unconditionally and then removed the baby after only a few days after birth. Because Nazca insane if you have to raise more than one child, it will be very difficult, so older young birds need to defeat smaller children to increase their chances of survival . '

A mature Nazca bird watching the herd.(Photo: David J. Anderson)

According to the study, high rates of hormones also cause young birds to survive a brawl that acts as a bully in adulthood. They often look for young birds in the herd and bite and bully those who are unable to defend themselves during their visit.

Scientists took blood samples from young Nazca ducks within 24 hours of hatching. Of the 15 groups with 2 eggs, both young birds were sampled. They also took blood samples from 15 young birds of only 1 egg. Later, researchers at the University of Maryland analyzed the hormone in the blood. By comparison, they also do the same thing with the blue-footed crazy bird - the close relative of the Nazca insane.

Researchers suspect that the Nazca wildbirds have a high rate of hormones that increase aggressiveness during the sensitive period of development as their time-consuming type of development is very vulnerable.

Some young Nazca insane birds have a higher rate of hormones related to their aggressive nature when they have siblings. Those who have to fight with siblings will become more aggressive bullies as adults than Nazca insane birds who have never fought when they hatched.

Anderson said: ' The rate of participation and the battle when newly hatched birds seem to have changed some of their social characteristics .'

Non-Nazca insane has three times the hormone-related rate of aggression than its less aggressive siblings - these are crazy blue-footed birds. The crazy blue-legged bird does not have life-and-death battles after hatching and does not become a bully at all when they grow up.