It’s no secret that city dwellers can be a bit aggressive: Whether they’re guarding their personal space on a crowded train, racing other commuters for a taxi, or just pushing their way down a crowded city street, many city dwellers aren’t just aggressive—they can be downright territorial. But human city dwellers aren’t the only ones with these kinds of tendencies. A recent study published in the journal Biology Letters found that urban birds may also be more territorial and aggressive than their more laid back rural counterparts.

In order to study how humans and human-built environments impact bird behavior, researchers at Virginia Tech decided to compare aggressive territoriality in urban and rural song sparrows. They identified two urban sites with heavy human foot traffic—the campuses of Virginia Tech and Radford University—as well as two rural sites (a farm and a park). They then played a recording of a male song sparrow to the male song sparrows at each site, observing how they reacted to the “intrusion” from a stranger.

Researchers found that urban sparrows were significantly more aggressive than rural sparrows: They approached the sound, flapped their wings angrily, sang loudly, then began singing a “soft song” (the term researchers use for the ominous, garbled noise birds make before attacking). Rural birds, meanwhile, responded to the recordings, but with less intensity.

Researchers aren’t sure why urban birds exhibit more aggressively territorial tendencies than rural birds, though they believe lack of space and limited resources might drive urban birds to become more protective of their territory. “A possible reason for this is that these birds have less space but better resources to defend,” researcher Scott Davies explains. “Living near humans provides better food and shelter, but it also means more competition for these limited resources.”

Researcher Kendra Sewall explains that the study was part of a broader effort to gauge the impact of human population growth on animals. "Predicting the impact that human population growth will have on wildlife requires studying the species that adjust and persist in human-impacted habitats," she says. "Suburban sprawl is a primary form of human habitat change and though many species can survive in our backyards, their behavior and physiology may change to cope with shifts in resources and with new disturbances."

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