That’s according to this article which suggests magpies are able to identify humans that have posed a threat to their nest and recognise them again. A team in South Korea made the discovery during routine research on a nest monitoring study. During this research it was found that when a researcher approached a nest he had previously climbed up to, the magpie behaved very aggressively. When someone approached the nest who had not previously approached the birds they would simply fly away. Despite trying to disguise the researcher who had previously disturbed the nest by having him wear different clothing, the birds would always identify him. American crows and Northern mockingbirds have also been found to have a similar ability. I guess the message here is, don’t upset magpies they will remember you.