Why you should become a volunteer urban biodiversity scientist

A few weekends ago, I joined 83,000 participants from around the globe to find this urban flora and fauna and share it with the world. The City Nature Challenge, or “bioblitz,” is an annual competition documenting nonhuman urbanites. Armed with no more than a smartphone and free time, nature lovers in nearly 700 cities uploaded more than 2.4 million wildlife photos to the platform iNaturalist.

These citizen scientists provide an invaluable glimpse into unlikely urban ecosystems, often in places scientists can’t venture into, such as backyards and private grounds.

“Urban areas are not like blank spaces on the map in terms of conservation value,” says Alison Young of the California Academy of Sciences, who co-founded the City Nature Challenge in 2016. “You just find things that you weren’t expecting, and things that are really important for people to know about.”

The bioblitz is the world’s largest biodiversity survey, according to iNaturalist, helping scientists craft conservation plans that recognize nature is everywhere. As the world rapidly becomes more urbanized, cities and backyards are becoming essential for saving biodiversity.

The teeming urban jungle

Cities are not “biological deserts,” as some have portrayed them. They act as bridges between natural reserves — even reservoirs for some wild populations — no matter how developed they might seem.

This year, volunteers sent in photos of more than 65,000 species, according to City Nature Challenge. La Paz, Bolivia, (population: 2 million humans) and Hong Kong (one of the densest cities in the world with a population of 7.3 million), each submitted around 5,000 observed species.

Mexico City, which has been an urban center for 700 years since the founding of the Indigenous capital of Tenochtitlan, is now the only place you can encounter a wild axolotl, a critically endangered amphibian.

Or you might travel to Los Angeles to meet one of the 30 new fly species discovered there during a brief, three-month search of local backyards and gardens.

In all, more than 400 cities globally overlap biodiversity hot spots. And researchers estimate that half of the urban area that will exist in 2050 has yet to be built.

How we make room for nature in our cities promises to shape the survival of plants and animals within them, as well as our own quality of life.

Why being an urban naturalist is good for you

Humans are now an urban species: Nearly 60 percent of the world’s population is crowded into cities covering 1 percent to 3 percent of the world’s surface.

As we’ve constructed these artificial environments, we’ve also lost something essential: daily immersion in the natural world that once helped keep us happy and healthy, say researchers.

In 2020, the average human lived roughly 6 miles away from undisturbed natural areas, roughly half a mile farther than two decades earlier, according to a 2022 study. This paucity is probably draining natural imagery from our culture as well: The frequency of nature-related words declined in popular books, songs and other creative works over the 20th century.

Yet this loss is at least in part a matter of perspective. We’ve given up looking for a natural world that never really left. Cities can give millions of people a regular, substantial encounter with wild plants and animals.

Study after study has found the presence of nature bolsters our mental and physical health, enhancing the quality and length of our lives. Even something as little as the view through a hospital window can help.

You just have to care to look.

Take Melbourne, Australia’s second-largest city. Surprisingly, write University of Melbourne researchers Mark McDonnell and Amy Hahs, 90 percent of the native plant species recorded over the past 100 years persists in the city, despite the loss of 90 percent of the original habitat.

But an “extinction debt” is hanging over the city — and many others. As habitats shrink, their capacity to sustain a diversity of species declines, a process that can take years or decades to play out. So even as residents can take in Melbourne’s wild flora today, much of it’s slated to disappear over the next century.

What you can do is document it. Researchers argue we have to better understand cities’ urban ecologies before we can restore and manage what remains. Then rebuild, block by block, backyard by backyard, the pockets of habitat that constitute these new ecosystems. Plots as small as one square meter, less area than a back patio, can make a difference.

Getting to know your neighbors

As for my own backyard, it only took a few minutes to meet a long list of species, natives and new arrivals alike including yellow-faced bumblebees, raucous Steller’s jays and a profusion of California flannel bush blossoms.

My Bay Area neighbors inspired me to aim higher. One snapped an encounter between a California slender salamander and a western forest scorpion in Los Gatos. Another scored the elusive, stunning silvery blue butterfly. A member of the local coyote pack posed for a photo.

But my personal favorite is a gray fox that appeared in Sarah Harris’s yard in El Cerrito, a town of about 26,000 people across the bay from San Francisco.

“We regularly have wildlife roaming our yard,” Harris wrote me. “I didn’t see it anywhere and then, when I was about to give up and head back in, I saw some movement up above me. There was the fox, walking across the top of the tall brink wall that separates our yard from our neighbor’s.”

“It didn’t seem fazed by me in the least,” she added.