The elegant Nazca booby (Sula granti), a seabird found in the eastern tropical Pacific, now claims the rather sombre title of being the first species in the wild to show evidence of social transmission of child abuse down generations. The very high density of booby colonies leads to frequent acts of violence against chicks while their parents are feeding out at sea, particularly by adults that have not bred that year. Recent research has found that there is a strong correlation between the number of incidences of maltreatment by unrelated adults experienced as a juvenile, and later perpetration of violence towards other chicks. Birds that were frequently abused when young are more likely to show aggression towards chicks in adulthood. It is suggested that this may be due to increases in stress hormones caused by the experiences, an imbalance which later triggers aggressive behaviour. Using the Nazca booby as a model could help us to learn more about the same phenomenon seen in humans.
Ref: Walker (2011) Abused baby boobies grow up to abuse other chicks. BBC News [link]