In 2007, for the first time in history, more people worldwide began living in urban areas than in rural ones, a demographic shift that also mirrors changes in the animal kingdom. Increasingly, wild animals are adapting to human-modified environments, becoming what experts call synanthropes—species that thrive alongside humans in cities. Despite their prevalence, many residents remain unaware of the complex biodiversity of urban wildlife and the critical roles these creatures play within city ecosystems.
Dan Werb, a social epidemiologist and author, explores these dynamics in his book “Our Wild Familiars.” Werb, who studies the social determinants of health, highlights the connections between human and animal lives in urban settings, explaining that many wild species are integral to maintaining ecological balance and supporting community sustainability.
Werb’s interest in zoonotic viruses led him to study the intersection of wildlife and urbanization. He notes that the trafficking of exotic animals into urban centers has amplified the risk of disease transmission, but not all urban wildlife poses such threats. Many species have adapted successfully to city life; for example, pigeons benefit from the absence of many natural predators, although recent urban predator shifts, including the presence of red-tailed hawks and coyotes, have introduced new challenges.
Biologists refer to this period in North America as the “great urban shift,” characterized by an increase in species, including larger mammals, moving into urban zones. This trend is driven by ongoing habitat transformation due to human development and the effects of climate change, which forces animals to seek refuge in cities after events like wildfires. Werb points to last year’s severe fires in Los Angeles as a case in point, where displaced wildlife were drawn into urban areas offering stable food and water sources.
The Los Angeles metropolitan area serves as an illustrative case given its diverse geography and socioeconomic variation. Here, biodiversity correlates with neighborhood wealth: wealthier areas tend to have larger lots, more green space, and fewer barriers like fences, supporting richer wildlife habitats.
Coyotes in Los Angeles exemplify the complexity of urban animal management. While often viewed as a nuisance, they are trapped within city boundaries by human infrastructure, restricting their movement and sometimes leading to conflicts with residents, such as pet losses. This phenomenon, known as an ecological trap, occurs when animals are attracted to urban environments for resources but face increased dangers there. Similar issues arise with other species, including black bears that scavenge in suburban garbage or seagulls abandoning their natural diets for easier human food.
Efforts to address these challenges include innovative infrastructure such as the Wallis Annenberg Wildlife Crossing over the 101 Freeway in Agoura Hills, the first of its kind in the United States. Designed to provide safe passage for animals across busy roadways, such crossings aim to restore natural movement patterns and reduce human-wildlife conflicts.
Beyond ecological and practical concerns, Werb emphasizes the psychological and biological benefits of urban wildlife to humans. The presence of birdsong, for example, has been shown to reduce stress, and interactions with animals foster a unique form of connection that can counteract the social isolation often exacerbated by technology. He suggests that experiencing mutual awareness with urban wildlife enriches human life and deepens our understanding of the shared environments we inhabit.
As urbanization continues to shape both human and animal lives, understanding and managing these complex ecosystems will remain a key challenge for cities worldwide.