You are what you eat: diet influences the social lives of birds

Today’s Video of the Day from the University of Bath confirms, for the first time, that there is a link between the diets of birds and their social and mating behavior. The existence of such a link was first proposed in 1964 by British ethologist, John Crook

According to the study, weaver birds that eat seeds are more likely to flock together and nest in colonies than the species that live in the forest and eat insects. Weaver birds in forest habitats were found to be solitary hunters. 

Furthermore, the researchers observed that seed-eating birds are often polygamous, pairing with multiple mates during each season. By contrast, the forest birds with insect diets tend to be monogamous.

The study was led by Professor Tamás Székely, an expert in the Milner Centre for Evolution at the University of Bath. 

“For birds that feed on seeds in the open savannah, flocking together improves feeding efficiency because it makes it easier to locate patches where there are abundant seeds,” explained Professor Székely.

“Flocking also lowers the risk of predation out in the open by providing them safety in numbers. However, in open habitats such as the savannah there are limited nesting sites, meaning the birds live together in a colony and this often leads to polygamous breeding.”

“On the other hand, forest-dwelling, insect-eating birds must search a wider area for food as insects are more widely distributed. The relatively safer, closed habitat of the forest provides lots of suitable nesting sites, so the birds don’t need to live close together.”

“This more solitary social system also means they are more likely to stick with the same mate during the breeding season. The associations between diet, habitat and social behavior in weavers have been suspected for decades, but this is the first time they have been proven by statistical analysis.”

“This study is particularly exciting because we’ve also shown the complex links for the first time between food type, grouping behaviour and mating systems using phylogenetic analysis in an unusually diverse group of songbirds.”

Video Credit: University of Bath 

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By Chrissy Sexton, Earth.com Staff Writer