Social bird species are less competitive

A team of researchers from Carleton University and the Cornell Lab of Ornithology has found that social birds tend to be less dominant and competitive than solitary birds. The researchers used a large citizen science dataset of interactions among birds foraging at backyard feeders in order to examine the relationship between sociality and dominance.

“We found that species’ sociality was inversely related to dominance,” explained study lead author Ilias Berberi, a PhD student in Biology at Carleton. “Using data collected from thousands of bird-watching volunteers, we measured the sociality of different species based on their typical group size when seen at bird feeders. Though some species are often found in groups, others tend to be loners. When we examined their dominance interactions, we found that more social species are weaker competitors. Overall, the more social bird species are less likely to evict competing species from the feeders.”

The scientists examined over 55,000 competitive interactions among 68 common bird species at backyard feeders, collected through Project FeederWatch, a Cornell Lab initiative which uses data collected by volunteers to monitor feeder birds from November to April every year. 

Although the investigation revealed a lower level of competitiveness in the case of social species such as the House Finch, the American Goldfinch, or the Pine Siskin, the experts found that such birds often gain the upper hand when members of their own species are with them, managing to successfully displace less social birds like the Northern Mockingbird or the Red-bellied Woodpecker.

“Being a social species certainly has its advantages,” said study co-author Eliot Miller, a postdoctoral researcher in Ornithology at the Cornell Lab. “Social species appear better defended against predators, and also may benefit from increased foraging efficiency.”

In addition, the researchers observed that, although social species have fewer competitive interactions with other species, they tended to compete more among themselves. 

“Overall, these results demonstrate that sociality can influence competition in ecological networks. More social species have decreased competitive ability as individuals, but they may gain competitive ability in groups,” the authors concluded.

The study is published in the journal Proceedings of the Royal Society B: Biological Sciences.

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By Andrei Ionescu, Earth.com Staff Writer

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