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L.A.'s Surprising Urban Biodiversity

Exposing the ecosystems in your own backyard.

By Jonathon Keats
Nov 10, 2017 6:00 AMNov 18, 2019 3:53 AM
Nigel Cattlin/Science Source


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For more than a century, the Natural History Museum of Los Angeles County has exhibited exotic specimens from around the world. But recently that global focus has shifted, as biologists recognize that LA itself is among the planet’s most diverse ecosystems. A new Urban Nature Research Center is enlisting citizen scientists to catalog species that they find in their backyards, from spiders to squirrels. Their goal is to better understand how biodiversity is affected by urbanization and globalization. Documenting the city’s urban wildlife is revealing patterns in migration and adaptation that may inform similar studies in other cities.

Indo-Pacific Gecko Hemidactylus garnotii

  • Indigenous to southeast Asia, these geckos are now found in Florida and Hawaii. Both those states supply non-native nursery plants to Los Angeles.

  • The critter’s populations are expected to spread. So far, they’ve been spotted in warehouse complexes and residential areas in Orange County, as well as Torrance.

  • Because it’s an all-female species, just one of these geckos can start a population. Angelinos have even observed eggs hatching during the winter, a remarkable feat because their native habitat is tropical, and LA’s climate is cooler and drier.

  • The geckos survive LA winters behind water heaters and refrigerators, which simulate tropical heat and humidity.

Jason Ondreicka/Alamy Stock Photo

Brown Widow Spider Latrodectus geometricus 

  • LA’s first brown widow was spotted by a child in a Torrance schoolyard in 2002. Now, it’s one of the 10 most common spiders in the region.

  • The brown widow, which probably originated in South Africa, has spread to warm habitats globally in the crevices of containers. Other spider species new to LA — such as the false widow — have likewise been accidentally imported.

  • Brown widows prefer living in artificial outdoor furniture versus plants and trees.

  • The brown widow has almost completely supplanted the native black widow. Although the two species are similar, unlike black widows that don’t reproduce in winter, the brown widow reproduces year-round.

Nigel Cattlin/Science Source

Chrysalis SnailLauria cylindracea

  • The chrysalis snail is critically endangered in some parts of its native range, including Switzerland and especially the German Rhineland. But at some point, it established new territory in British Columbia, perhaps from a flower brought over from Denmark.

  • The snail has now arrived in LA — specifically the UCLA campus. The university’s extensive landscaping offers many habitats for the non-native snails, which can survive under stones, on tree bark, and among grass and leaf litter.

  • Unlike most snails, the chrysalis gives birth.

  • This snail is just 4 mm long and identifiable by a single, small “tooth” jutting out from the opening in its shell. The tooth is thought to provide protection against predators.

Marc Moritsch/Getty Images

Western Gray SquirrelSciurus griseus

  • Western gray squirrels eat acorns and pine nuts in the heavily forested oak-conifer woodlands of the West. But the species is struggling with urbanization in LA. Over the past century, they’ve become increasingly rare.

  • Much of the territory formerly occupied by western gray squirrels is now dominated by eastern fox squirrels (Sciurus niger), which evolved in the open forests of the eastern U.S. and were first introduced to LA in 1904.

  • While gray squirrels spend much of their lives in trees — and depend on canopy connectivity — fox squirrels will forage far and wide. They thrive in urban and suburban areas and will eat anything from acorns to pizza.

  • Western gray squirrels are still occasionally found in the Verdugo Mountains north of Burbank. They can also be seen in Griffith Park’s Fern Dell, a habitat they share with the eastern fox squirrel. (Being larger, they’re still able to boss around their eastern relatives.)

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