Magpies recognise and 'scold' individual humans
Magpies recognise and "scold" humans who they perceive to be threats to their nests, scientists have found.
During a routine nest-monitoring study a research team in South Korea discovered that the birds recognised an individual that had previously climbed up to and disturbed their nests.
When that person approached trees in which the birds were nesting, the magpies called out and pursued him.
The findings are published in the journal Animal Cognition.
One of the researchers, Sang-im Lee from Seoul National University, explained that the findings were "accidental observations".
SMART AND SOCIABLE
- Magpies (Pica pica) roost together and, during the breeding season, they gather in "magpie parliaments" where birds look for mates.
- They are part of the corvid family, which includes crows and ravens. These birds have also shown impressive cognitive skills, including tool use and problem solving.
- Magpies appear black and white. But their wing feathers have a blue iridescent sheen and their tails have a green gloss.
Her colleague, Wonyoung Lee, climbed up to the birds' nests during the breeding season of 2009.
During a routine nest-monitoring study, "[Wonyoung] would count their eggs, measure the chicks, and take blood samples from them," explained Dr Lee.
But when Wonyoung later passed close to a nest that he had previously climbed up to, the adult magpies behaved very aggressively towards him, following him and making loud alarm calls.
To find out if the birds specifically recognised the scientist, the team carried out a series of experiments. They compared the birds' reactions to Wonyoung to their response when a stranger approached the trees in which the birds nested.
When two people approached a magpie nest that Wonyoung had previously climbed to, the birds would scold both of them, explained Dr Lee.
But, she told BBC Nature, "as the two moved away in different directions the magpies followed Wonyoung."
The researchers even tried disguises to fool the magpies - Wonyoung would give the other researcher his hat - but the birds would still pursue him.
"And when people who had never climbed to the nests approached them, the birds just flew away," said Dr Lee.
The researchers tested 11 pairs of magpies and more than half of the birds appeared to recognise and react specifically to Wonyoung.
Magpies are actually the third bird species that have been found to recognise humans. In just the last year, researchers discovered that American crows and Northern mockingbirds have the same ability.
Dr Lee commented: "We suspect that they use facial features, but we haven't conducted experiments to properly test that hypothesis."
He believes that the birds might have evolved this capability to help them survive in an urban, human-dominated environment.
The study was carried out in collaboration with Ewha Womans University, Seoul and the Polish Academy of Sciences.