In 2016, Lila Higgins at the Natural History Museum of Los Angeles County and Alison Young at the California Academy of Sciences started a friendly competition to see which of their cities — Los Angeles or San Francisco — could identify the most species of plants and animals over a week. Harnessing the enthusiasm of citizen scientists, they launched the City Nature Challenge. Three years later, 159 cities around the world participated in this year’s competition, making some 960,000 wildlife observations, identifying tens of thousands of species, and discovering new ones in the process.
According to this year’s “leadership board” at the City Nature Challenge, Cape Town, South Africa took the top prize with 53,000 observations and 4,500 identified species, contributed by 1,100 participating citizen scientists. La Paz, Bolivia, made 46,000 observations and identified 3,000 species, with the help of 1,500 citizen scientists. In third place is San Diego county, California, which made 38,000 observations and identified 3,000 species through the work of 1,100 local scientists.
Stella Tarnay, co-founder of Capital Nature (formerly Biophilic DC), said that Washington, D.C. placed in the top 20 in terms of the number of participating citizen scientists, observations, and species identifications. Some 1,200 people participated through 120 events to collect nearly 30,000 observations and identify 2,250 species. While D.C. did well on observations, the city fell short on species identification.
Around the world, City Nature Challenge citizen scientists used the free iNaturalist app, which was started by the National Geographic Society and the California Academy of Sciences a decade ago, to crowdsource the identification of biodiversity. More than a million citizen scientists are now active on the app and have helped each other identify 180,000 species observed 16 million times in cities and the wild. The app is now also assisted by artificial intelligence.
Data was aggregated into local city challenge groups within iNaturalist. Once set up on the app, citizen scientists take photos of native or cultivated trees and plants, as well as fungi, insects, reptiles, and mammals. According to Tarnay, the scientists who run iNaturalist prefer “volunteer” plants, meaning they grew wild in a particular spot and weren’t purposefully planted there.
iNaturalist encourages users to take multiple photos of a species, add in notes, and mark the location of the species. Once uploaded, the app then considers that an observation and then offers up possible identifications. Once someone has confirmed the identity of a species, it becomes a “casual grade” identification. Once two users on the app have verified the species, the identification is determined to be “research grade.”
For one observational adventure on the National Mall — organized by the Potomac Chapter of ASLA and AIA DC’s committees on well-being and urban design and supported by Capital Nature — urban designer Michiel de Houwer created a handy map, identifying where different types of animals may be found via 5-minute walk zones. Smartphones in hand, we trekked to the National Museum of the American Indian to find native plants.
At the end of the week-long bioblitz in D.C., Tarnay said the most identified species were:
Plant: Mayapple (Podophyllum peltatum) – 279
Bird: American Robin (Turdus migratorius) – 143
Mammal: White-tailed Deer (Odocoileus virginianus) – 111
Butterfly: Eastern Tiger Swallowtail (Papilio glaucus) – 68
Amphibian: Eastern Red-backed Salamander (Plethodon cinereus) – 66
In addition to helping map the extent of biodiversity and getting more young people outdoors to connect with nature, City Nature Challenge has led to the discovery of new species. One estimate states there are 8-9 million species on the planet, but only around 1.75 million have been discovered, identified, and catalogued, leaving 80 percent unknown. More recently, a group of scientists estimated that there could be up 1 trillion species on the globe if we include bacteria, archaea, and microscopic fungi, which could mean some 99.99 percent remain undiscovered.
The latest dire report from the United Nations makes clear why the public needs to engage with biodiversity. The 1,500-page report produced by 145 scientists from 50 countries found that up to one million plant and animal species are threatened with extinction due to our degradation of the natural environment and climate change. Today, less than 70 percent of the forests that existed prior to the Industrial Revolution remain, with 100 million hectares cleared since 1980. Some 50 percent of coral reefs and 85 percent of wetland have been lost, while a third of the planet is now used for agriculture. The world’s most famous biologist — E.O. Wilson — has called for preserving half the Earth before it’s too late.
As this year’s challenge shows, cities like Cape Town are actually biodiversity “hot spots.” Documenting and then protecting pockets of biodiversity in cities may seem small in the grand scheme of things, but urban wildlife refuges are critical for the plants and animals that rely on them. More cities are becoming refuges for animals turned out of their natural habitats, spurring on further adaptation and evolution in ways we don’t yet understand.
In the end, the sustainability and resilience of humanity depends on the preservation of Earth’s biodiversity.