If you thought nepotism could have only been a human trait, you were wrong — so wrong. Recent research has shown that nepotism can be found in species like birds.
The research, conducted by Martha Nelson-Flower — a post-doctoral fellow at UBC’s faculty of forestry — and Amanda Ridley of the University of Western Australia, was focused on behavioural observation of the southern pied babbler, a bird native to Botswana, Namibia, South Africa and Zimbabwe. It’s a black and white bird that lives in cooperative breeding groups. These groups are made up of a dominant pair and subordinates. The dominant male, which is also the breeder, holds power over the group while the subordinates — often the dominant’s offspring — help with breeding.
“Nepotism has likely played a vital role in the evolution of family life in this species,” explained Nelson-Flower.
Think of this species like a royal family — the dominant bird is the king and the subordinates are in line for the throne and just like humans, the babbler shows signs of nepotism.
“This preferential treatment of male birds was not observed amongst the females,” explained Nelson-Flower. Due to their aggressive nature, female babblers don’t show signs of nepotistic behaviours nor were they affected by it. Nelson-Flower added that, unlike the males, females do not wait around for a dominant space to free up. In fact, they search for weak female dominants and seize power from them by simply attacking or booting them out of the group.
Nelson-Flower stumbled upon patterns of nepotism in the data and decided to further investigate them.
“I was looking for males that were living in the group that were unrelated to the dominant male. And I couldn’t find many of these unrelated males. I couldn’t understand why at first,” Nelson-Flower explained.
She counted how many days a subordinate male stayed in a group when the dominant male was unrelated. The result showed the more closely related a subordinate is to the dominant, the longer it will stay in the group. Nelson-Flower also found that the longer a subordinate stayed in the group, the more likely it was to become dominant.
“The way to get dominance for a male is to hang around and wait for a space to free up in a local group or even in their own group,” said Nelson-Flower. “If that dominant male dies, they might be able to inherit dominance. It is always the eldest one in the group who does, like a lineup or queue.”
Why would a dominant male care if he had a stepson in the group? Nelson-Flower said it was because, when ascending to the ‘throne’, an unrelated subordinate creates a disadvantage to the dominant male’s own sons who are younger.
“We do see a dominant kicking out a subordinate sometimes. The subordinate could be given a lot of low-level aggression by the dominant for instance or maybe the dominant turns around one day and kicks it out,” explained Nelson-Flower.
“People know about nepotism in a human context, but it’s interesting and important to realize that it happens across all contexts where there is power. Where you can give the benefit of power to a relative, there will be nepotism.”
Share this article
