Ambika Kamath | Updated on September 12, 2014

Blink Blue Tailed Bee Eater Divyaraj Shah.jpg

Blink Little Green Bee Eater Divyaraj Shah.jpg

Meet the colourful avian that lives in some of the most complex societies

Awhile ago, I was asked what my favourite bird is. I took some time to consider the question, but my answer has since been unwavering — bee-eaters. Why bee-eaters? Because of their brilliant colours, their lovely swooping flight, and the endearing manner in which they smash insects against tree branches or electricity wires, thus ridding bees of their stings before eating them. Soon after declaring bee-eaters as my favourite feathered creatures, I learnt yet another reason that validated my choice — bee-eaters live in some of the most complex societies known in birds. And these societies are built around the simplest of nests, nothing more than holes dug in the sand.

A solitary bee-eater’s nest is easy to miss, unless you happen to spot an adult flying into its unremarkable hole. If you’re lucky, you may see them dart briefly into their nest openings and quickly flick out some sand with their feet. But many species of bee-eaters live in huge colonies, their numerous nest-holes pock marking sandy cliff faces, packed so densely that one wonders why the cliffs don’t collapse. Each nest serves as a nursery to the chicks of a single pair of bee-eaters, but if you watch how many different individuals enter and leave a nest, you’ll find that more than two adults can act as parents to a single clutch. Who are these birds, and why do they help raise someone else’s offspring?

More curious than the mere presence of helpers is the fact that, in some species, these helpers may help at several nests. This generosity begins to make sense when we learn that these species of bee-eaters live in little joint-families, or ‘clans’. Each clan comprises a few pairs plus several unpaired or non-breeding individuals that assist in raising others’ offspring. Individuals join a clan either by being born into it, or by ‘matrimony’, inducted into the clan of the individual they pair up with, in time, leading to clans of closely related individuals and their mates. This social structure ought to sound familiar to you. One can almost imagine turning on the television to watch Kyunki Saas Bhi Kabhi Bahu Thi — the Bee-Eater Edition.

Does a joint-family structure explain why helpers help? It does, if you consider why organisms reproduce in the first place. From the perspective of evolution by natural selection, organisms reproduce to ensure the persistence of their genes in future generations. But since you inherit half your genes from each parent and therefore share half your genes with each sibling, your own reproduction isn’t the only way to propel some of your genes into the future — you could help a family member reproduce successfully instead. This logic is especially compelling when times are tough and you aren’t likely to reproduce successfully yourself — before you’ve found a mate, for instance, or in years when food is scarce, or if your chicks get eaten by a ravenous snake before they leave the nest. Helping relatives raise their chicks successfully ensures that at least some of your genes make it into the next generation, albeit indirectly. It’s not quite as good as raising your own offspring, but isn’t that exactly what you hope you can count on family for — to help you make the best of a bad situation?

( Ambika Kamath studies organismic and evolutionary biology at Harvard University)

Published on July 11, 2014

Follow us on Telegram, Facebook, Twitter, Instagram, YouTube and Linkedin. You can also download our Android App or IOS App.

This article is closed for comments.
Please Email the Editor