Blood may be thicker than water when it comes to humans relationships – and it appears that the same is true of jackdaws after scientists found they readily switch friends to gain food but stick with family even at the risk of going hungry.
A study of jackdaw colonies in west Cornwall established that the small crows ditch old friends and make new ones if it helps them get rewards but stick with family through thick and thin.
The scientists presented wild jackdaws – highly gregarious birds – with a task in which access to tasty mealworms depended on which individuals visited together.
Though the birds soon switched friends to get the best rewards, they stuck with their offspring, siblings and mating partners (jackdaws pair for life) no matter the outcome.
The study, part of the decade-long Cornish Jackdaw Project, provides new insights on how some animals manage social relationships.
Alex Thornton, a professor of cognitive evolution at the centre for ecology and conservation at the University of Exeter’s Penryn campus in Cornwall, said: “We monitor hundreds of wild jackdaws, each of which is fitted with a tiny PIT tag – like the transponder chips used for pet cats and dogs – embedded in a leg ring.
“In this experiment we randomly assigned jackdaws to two groups – A or B – and programmed a pair of automated PIT tag-detecting feeders to provide mealworms only if individuals from the same group (AA or BB) visited together.”
If birds from different groups arrived together – A with B – the feeders would remain closed. Solo birds would get grain, but not the more desirable mealworms.
Thornton said: “The idea was to find out if they could readjust their social associations. They might have friends in the wrong group. Do you ditch them and start to hang out with individuals who are in the right group?
“The jackdaws turned out to be very strategic, quickly learning to ditch friends from the other group so they could get the best rewards. However, they made an exception when it came to their close relations even if they get nothing.
“The fundamental idea is that if you need to keep track of interactions you have had with other individuals, remember the outcomes of those interactions and use those to adjust your behaviour. What we were able to do here was test the idea: can individuals keep track of the outcomes of past interactions and update their relationships. It turns out they can.”
Thornton said jackdaws were an excellent subject matter as they were clever and had dynamic social networks. “You’ve got individuals coming and going so beyond their strong relationships, they have lots of other associations. There’s quite a lot to remember. There are parallels with human society.”
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Michael Kings, of the University of Exeter, said: “These results have important implications for our understanding of the evolution of intelligence as they show that being able to track and remember information about social partners can bring benefits.”
Josh Arbon, from the University of Bristol, added: “Our findings also help us to understand how societies emerge from individual decisions.”
Established in 2012, the Cornish Jackdaw Project involves three colonies, with more than 2,500 individually recognisable, colour-ringed and PIT-tagged jackdaws.
The findings are set out in a paper, “Wild jackdaws can selectively adjust their social associations while preserving valuable long-term relationships”, published in Nature Communications.
