Investigations encompassing a multitude of avian species across Europe, including familiar birds like great tits, house sparrows, and blackbirds, indicate their capacity to discern human gender and exhibit differential responses. However, the underlying mechanisms for this phenomenon remain elusive.
The western yellow wagtail (Motacilla flava), a small passerine bird in the family Motacillidae. Image credit: Sci.News.
“The conventional behavioral response observed in animals encountering potential threats is evasion,” stated Professor Daniel Blumstein of the University of California, Los Angeles, and his research associates.
“Ascertaining the advantages and disadvantages associated with flight is a critical element in managing the perils posed by predators.”
“The distance at which flight is initiated (FID) is frequently employed as an instrument to scrutinize the cost-benefit trade-offs inherent in predation risk.”
“FID quantifies fearfulness, measured as the spatial separation between an observer and a target organism at the moment the targeted individual, such as a bird, takes flight.”
“Even when assessed in contexts devoid of predatory intent, but in response to approaching humans, FID serves as a credible indicator of predator-associated apprehension in urban avifauna.”
The recent investigation, carried out across five European nations—the Czech Republic, France, Germany, Poland, and Spain—involved male and female volunteers traversing urban parks and green spaces in a linear fashion toward avian subjects.
The scientific team observed that individuals representing the male gender were permitted to approach birds approximately one meter closer, on average, before eliciting an escape response, in contrast to female approaches.
These findings demonstrated remarkable consistency across all participating countries and encompassed the 37 species under scrutiny, ranging from those with a propensity for early flight, such as magpies, to those that tend to depart at a later stage, like pigeons.
“Our research illuminated that, after controlling for other factors contributing to significant variations in FID, birds, on average, exhibited a tendency to initiate flight from an approximately greater distance of one meter when approached by women compared to men,” the researchers reported.
“The birds displayed reduced tolerance towards women relative to men, a pattern that remained consistent geographically.”
Based on their observations, the authors posit that urban bird populations possess the capability to differentiate the sex of approaching humans.
Nevertheless, the specific attributes that birds are perceiving, or the reasons for their heightened wariness of women, remain an enigma.
“I am fully convinced by our findings that urban birds react diversely based on the gender of the individual approaching them, but I am currently unable to offer a definitive explanation,” Professor Blumstein commented.
“We utilized cutting-edge comparative analytical methodologies that affirmed the uniformity of our results across various urban environments and bird species; however, a conclusive rationale is still wanting.”
“As a woman actively engaged in this field, I found it surprising that birds responded to us differently,” added Dr. Yanina Benedetti, a researcher affiliated with the Czech University of Life Sciences Prague.
“This study underscores the perception of humans by urban wildlife, carrying significant implications for urban ecology and the principle of equality within scientific endeavors.”
“Numerous behavioral studies operate under the assumption that a human observer is a neutral entity, but this premise proved unfounded for the urban birds in our investigation.”
The research group has formulated several conjectures regarding the cues birds might be detecting, including pheromones, variations in body form, or distinct gaits.
“This aspect is perhaps the most intriguing facet of our study,” remarked Dr. Federico Morelli, a researcher at the University of Turin.
“We have identified a phenomenon, but its underlying cause remains genuinely unknown.”
“Nonetheless, our findings prominently highlight the birds’ remarkable aptitude for assessing their surroundings.”
“Urban birds clearly respond to subtle signals that are not readily apparent to human perception,” Dr. Benedetti stated.
“Subsequent investigations could concentrate on individual variables such as locomotion patterns, olfactory cues, or physical characteristics, evaluating them discretely rather than aggregating them under the umbrella of observer sex. This approach would facilitate the identification of the precise signals birds are apprehending.”
The research outcomes were formally presented in the February 2026 publication of the esteemed journal People and Nature.
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Federico Morelli et al. 2026. Sex matters: European urban birds flee approaching women sooner than approaching men. People and Nature 8 (2): 316-326; doi: 10.1002/pan3.70226
