Like humans, abused birds grow up to be bullies

Just like humans, birds who are abused when they are young often grow up to be abusers, a new study has found.

In particular, for one species of seabird in the Galápagos, called Nazca boobies, the child abuse “cycle of violence” found in humans plays out in the wild.

Among this species, in which victimization by adults on other birds’ chicks is widespread, traumatic abuse of developing young significantly increases the chances those maltreated individuals will exhibit the same maltreatment later in life as adults, the report said.

“We were surprised by the intense interest that many adults show in unrelated young, involving really rough treatment,” said Wake Forest Professor of Biology Dave Anderson, who led the study with Wake Forest graduate student Martina Muller.

“A bird’s history as a target of abuse proved to be a strong predictor of its adult behavior,” he added.       

 Among Nazca boobies, victimization by adults on other birds’ chicks is widespread.

They raise solitary nestlings on the ground and frequently leave their offspring unattended while foraging at sea. So, there is much opportunity for adult birds to bully and beat up neighbour nestlings.

The abusive adults patrol the breeding colony, searching for unguarded chicks. They frequently bite and peck the chicks, and even make sexual advances, sometimes leaving the chicks bleeding and stressed. Female adults show more aggressive behaviour than males do, on average.

The study has been published in the ornithology journal, The Auk.