San Diego's unparalleled biodiversity is explored in the new PBS Nature documentary – San Diego Union-Tribune

Ask any San Diegan what the city's motto is and they'll say, “America's Finest City.” However, what most San Diego residents may not know is that it is also the wildest city in America.

Thanks to its unique geographic interface of ocean, mountains, deserts, wetlands and urban development, San Diego County is considered the most biodiverse county in the mainland United States, according to the Nature Conservancy.

That's the theme of “Nature – San Diego: America's Wildest City,” premiering Wednesday at 8 p.m. on PBS stations and the PBS app. A big-screen version of the film, titled “Wild San Diego,” will follow on November 22 for a seven-year engagement at the San Diego Natural History Museum.

“San Diego: America's Wildest City” was written by Nate Dappen and Neil Losin, co-owners of San Diego-based Day's Edge Productions, which co-produced the 52-minute film with WNET Group and Terra Mater Studios.

Past Day's Edge film projects include the six-part PBS Science documentary series “Human Footprint” (2023), “Serengeti: Nature's Living Laboratory” (2019); and the Inland Passage paddling adventure documentary “The Passage” (2019), among others.

Dappen said he, Losin and their production team have been working on the “Wildest City” project for two years. It's about how San Diego's wildlife has adapted and survived in a landscape dramatically altered by humans over time, and the challenges and opportunities these species face today.

“The first day I arrived in San Diego and went to the beach at sunset, I looked out at the ocean and listened to the sound of the surf, seagulls and seals and knew that this wonderful place would become my home,” said Dappen. “What I didn’t realize that day was how rich this landscape was. I began exploring and was amazed by the diversity of ecosystems here – deserts, mountains, chaparral and the great Pacific Ocean, all within an hour's drive. I knew I wanted to make a film that celebrated a different, spectacular side of America’s most diverse county.”

The film looks at a handful of wildlife species that are not only native to San Diego County, but have also either adapted to or been harmed by the presence of humans who came to the region 12,000 years ago and spread around the 500th century. times have increased to 3.3 million in the last 100 years. The biggest impact humans have had on wildlife, according to the documentary, is the way we manage our water resources.

Among the many species observed in the documentary are grebes, red-eyed waterbirds that nest in man-made reservoirs and lakes. There's also the Allen's hummingbird, which now nests comfortably in urban backyards, where it can collect nectar from manicured gardens and sip from hummingbird feeders filled with sugar water. There are the Pacific seals, which each year take over the 1931 man-made kiddie pool in La Jolla as a breeding ground for their young.

Ground squirrels have happily moved their dens from open fields to public parks that are abundant with irrigated grass, plants, trees and water. And desert birds, bobcats and coyotes are increasingly relying on pools, ponds and fountains in people's backyards as a source of water and bathing.

The film also includes sections about some of the region's natural wonders, such as Grunion, the silver fish that spawn on local beaches during the spring tide; the bioluminescent blue tides caused by single-celled algae called dinoflagellates; and wildflower splendor in the Anza-Borrego Desert.

The documentary does not delve deeply into the threat that development, drought and climate change pose to local plant and animal life, but it does show some of the unexpected results.

For example, the city of San Diego recently stopped using automated sand maintenance machines on its beaches during grunion season because the heavy machines were crushing millions of eggs laid beneath the sand. It also shows that grebe nests upstream are often destroyed when heavy rains force water authorities to open dam floodgates. It explains that there were no crows in San Diego until the 1980s, but they were drawn to the area as a fertile hunting ground for birds, squirrels and other prey. And it shows how the massive border fence separating the U.S. from Mexico has cut off roaming species like deer and coyotes from previous water sources.

Dappen and Losin met in Costa Rica in 2008, where they were both doing field research for their doctoral dissertations. In 2010, after discovering they had a shared passion for nature photography and filmmaking, they abandoned plans for academic careers and founded Day's Edge, which has produced educational and interest films about nature, wildlife, agriculture, anthropology and the environment.

Originally published: November 5, 2024 at 11:53 am PST