Chicks abused by older birds are more likely to grow up to become abusers themselves, scientists have found. Researchers studying a colony of Nazca boobies, a colonial seabird, found the birds perpetuate a “cycle of violence”.Juvenile birds that are maltreated by older, non-relatives grow up to become more violent towards other chicks.
It is the first evidence from a wild animal that, as in humans, “child abuse” can be socially transmitted down the generations.
Details of the discovery are published in the journal The Auk by Martina Müller, David Anderson and colleagues from Wake Forest University, North Carolina, US.
Nazca boobies are sea-going birds that live in the eastern tropical Pacific, nesting on the Galapagos Islands, and on islands off the coasts of Equador, Peru and Colombia.
Both parents tend to raise a single chick each year, feeding mostly on fish and the occasional squid.
The birds nest within dense colonies, and this proximity to each other encourages bouts of violence to break out.
While parent birds are away feeding at sea, non-breeding adults seek out unguarded nests and attempt to interact with the chicks within.
These can be positive interactions, but frequently they are abusive; the visiting adults try to perform sexual acts on the chicks or act aggressively toward them.
“The maltreatment of nestlings by adults is really obvious,” Dr Anderson told media. “Essentially all nestlings experience some maltreatment.”