City Nature Challenge gets more people observing nature — and more data for scientists

San Diego Natural History Museum botanist Jon Rebman points to his screen.

" I'm gonna show you the power of iNaturalist," he said, with the glee of a kid sharing a favorite toy.

 iNaturalist is a smartphone app that identifies and logs nature — from botany to insects, sea life and birds.

It's pretty simple: Snap a photo of a plant or critter, upload it to iNaturalist, and it instantly suggests an ID. It's almost like Pokémon GO but for science.

Then, once the photo is uploaded, experts and scientists weigh in and verify your findings.

Arts & Culture

Scientists are still mapping plants. How the public is helping — with an app

Julia Dixon Evans

Anthony Wallace

Scientists say we’ve barely scratched the surface when it comes to understanding and mapping the plants around us. In this episode, we meet the everyday people using an app called iNaturalist to help discover, document and protect biodiversity — sometimes even ending up in scientific papers.

Listen • 32:21

The rise of iNaturalist — and the community scientists using it — means a vastly expanded data set for scientists.

As an example, Rebman pulls up a cactus with 59 official specimens mapped in the region. These are official museum specimens and, before the era of iNaturalist, this is the extent of the data scientists had to work with. Fifty-nine specimens is great, he said.

But then he toggles his screen to also show iNaturalist observations. The map floods with dots — 6,500 additional locations of this cactus in San Diego County.

San Diego Natural History Museum's San Diego Map Atlas

"That really changes our knowledge of what is where," Rebman said. "It's a crazy amount of data. So that's why I do it, so that we better understand that diversity — where it is, and we can use that to better protect the species there."

Rebman is also rooting for San Diego to win this year's worldwide City Nature Challenge.

"We've always done OK as a community," Rebman said of San Diego's previous participation in the challenge. Then he added, conspiratorially: "I think we can do better."

Julia Dixon Evans

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KPBS

 To join the Challenge, attend a guided hike or "bioblitz" presented by SDNHM, San Diego State University Biodiversity Museum and the UC San Diego Natural Reserve System.

Or just post your own photos as you explore the nature in your neighborhood. All wild plants and animals count, even non-native species. Join the City Nature Challenge 2026: San Diego County project on iNaturalist to have your identifications contribute to San Diego's hopeful victory.

The challenge runs April 24 through 27.