City Birds Bolt Sooner When a Woman Walks Up

Pigeons, crows, robins and blackbirds in seven cities around Europe share a habit nobody can explain. They let a man walk about 3 feet (0.9 meters) closer than a woman before they fly.

An international team that included UCLA behavioral ecologist Dan Blumstein reported the result in a journal of the British Ecological Society. The birds numbered upward of 2,500, from 37 species, living in Spain, France, Poland, Germany or the Czech Republic.

The experiment was built to rule out the obvious suspects. In each city, a pair of expert ornithologists, one man and one woman, approached at the same slow pace from comparable distances. They were matched for height and build, wore similar colors and tucked away any long hair.

So what are the birds reading? Blumstein suggests gait, since pelvic anatomy differs between the sexes and shapes a stride, though the team did not specifically control for walking style. Scent or hormones strike him as unlikely at those distances. He does think a theory floated on Reddit merits a formal test. Birds see ultraviolet light, and sunscreen, including the kind blended into makeup, might stand out to them.

Birds join a short list. Earlier work found lab rodents more anxious in male hands, and monkeys and dogs have been reported playing favorites too. No one had seen it in birds before, which hints that experiments staffed by one sex alone could be skewed by that choice.

The team hopes to dig through hundreds of earlier studies logging how close people got to more than 150,000 birds at the moment they flew.

Height, build, hair and wardrobe were all matched. Somewhere in a European square, a pigeon spotted a difference anyway.

Read the full story at UCLA, May 20, 2026

Hot Take: Female birders now hold a peer-reviewed excuse for every warbler that flushed before the photo. Male birders should consider whether that extra 3 feet (0.9 meters) was ever really skill.