African bird shows preferential treatment toward male subordinates

A new research published in “Biology Letters”, suggests African desert-dwelling birds prefer their biological sons and alienate their stepsons.

“Nepotism has likely played a vital role in the evolution of family life in this species,” said Martha Nelson-Flower, a postdoctoral fellow at the University of British Columbia’s faculty of forestry.

The group’s dominant male bird decides which of the subordinate males to tolerate. Nelson-Flower’s research reveals subordinate male birds spend less time in a group if they are unrelated to the dominant male bird. The subordinate males are actually sent out of the group by their stepdads and in some instances by their brothers-in-law. They are then forced to live alone or to join other groups as subordinates.

The species is the southern pied blabber, a black and white bird found in Botswana, Namibia, South Africa and Zimbabwe. The chicks are raised by both parents as well as other adult birds and live in groups. The size of the groups range from three to 14 birds.

However, this kind of preferential treatment was not seen among the females.

“The research is some of the first to show that the sex of both dominant and subordinate birds, and the genetic relationship between them, has a significant impact on their family groups and cooperative breeding behaviour,” said Nelson-Flower.

The researchers used data from 11 years of observation.

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