Study of woodpecker social groups sparks debate

March 8, 2017, University of St Andrews
Study of woodpecker social groups sparks debate
Acorn Woodpeckers, Summerhaven, AZ. Credit: Allan Block

New research from the University of St Andrews has sparked debate about what it takes to live in stable, long-lasting social groups.

Investigation of the brain-size of woodpeckers, which often live in stable social groups, has revealed that the brains of are smaller than would be expected of individuals required to deal with the politics of social living: , manipulation and deception.

Researchers conclude the birds are so successful at supportive community living that they have been able to disinvest in brain tissue, challenging social brain theory as we know it.

Professor Richard Byrne explains: "It's been known for many years now that animals like primates, and several other kinds of mammal, have larger brains in species that live long-term in social groups: other things being equal, the larger the typical size of their groups, the larger the brain. That correlation supports the 'Machiavellian intelligence' or 'social brain' theory, which identifies dealing with other individuals as one of the most challenging mental problems for animals."

Group living may be important for survival – monkeys, for instance, live in groups to reduce the risk of predation – but it presents challenges. Group members inevitably compete for resources, including food and mating, and being smart helps.

It now seems birds may be the exception to this rule. Natalia Fedorova used a summer internship in the School of Psychology to test whether theory holds in stable communities of birds.

"I went to the London Museum of Natural History," Fedorova describes, "and measured the size of the brain cavity in preserved specimens of dozens of different species. Then we categorized their social system, based on a survey of the literature, as solitary, pair-living or group-living."

Professor Byrne continues: "Picking out a genuine effect is tricky; because body size also affects brain size, and because closely related species may be similar just because they are related. So we needed to use powerful modern statistics. We turned to Dr Cara Evans, at that time in the School of Biology, who supervised all the analyses and their interpretation."

The trio have now published their findings in Royal Society journal Biology Letters.

Remarkably, they found the opposite of what social theory would predict: the group-living woodpeckers had the smallest brains, and whether or not pairs lived together over years or associated only in the brief mating system made no difference to . The researchers conclude that long-term in birds must be socially quite different to those of mammals, where competition is an intrinsic part of the background.

Explore further: Bigger brains outsmart harsh climates

More information: Living in stable social groups is associated with reduced brain size in woodpeckers (Picidae). Biology Letters. DOI: 10.1098/rsbl.2017.0008

Related Stories

Bigger brains outsmart harsh climates

December 22, 2016

It helps to have a larger brain if you're living in an extreme climate, according to a study of birds published in Nature Communications. The research suggests that birds have evolved larger brains to cope in harsh environments ...

Socialising led to bigger brains in some mammals

November 23, 2010

( -- Over millions of years dogs have developed bigger brains than cats because highly social species of mammals need more brain power than solitary animals, according to a study by Oxford University.

Wild cat brains: An evolutionary curveball

October 31, 2016

The brains of wild cats don't necessarily respond to the same evolutionary pressures as those of their fellow mammals, humans and primates, indicates a surprising new study led by a Michigan State University neuroscientist.

Recommended for you

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...

EPA adviser is promoting harmful ideas, scientists say

March 22, 2019

The Trump administration's reliance on industry-funded environmental specialists is again coming under fire, this time by researchers who say that Louis Anthony "Tony" Cox Jr., who leads a key Environmental Protection Agency ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.