California wildlife: Why are so many turtles in LA parks?

Last year we started asking readers to do this send us your urgent questions via Los Angeles and California.

Every few weeks we put the voting questions and ask the readers to decide which question we should answer in the form of a story.

This question, posed by Dee Villalobos, was included in one of our recent reader polls: How do turtles survive in LA’s parks?

Imagine meeting friends for a picnic at your favorite LA park. They scan the grass for the best place to put up a blanket and decide on a shady spot near the pond. As you chat and enjoy your lunch, you notice a couple of turtles basking and smiling on a sun-dappled log. It’s one of the beauties of living in Los Angeles—that in the midst of a sprawling metropolis, wildlife coexists alongside humans.

One problem, though: By and large, the turtles you see in Los Angeles city parks aren’t native to California.

Instead, many are native to countries hundreds of miles away the Mississippi Valleyfrom Illinois to the Gulf of Mexico (although their natural range may extend as far south as eastern New Mexico, according to the California Department of Fish and Wildlife).

But Southern California has a native turtle.

Once upon a time, the native terrapin “lived all over the rivers and creeks of the greater LA area,” said Brad Shaffer, director of UCLA’s La Kretz Center for California Conservation Science and distinguished professor in the Department of Ecology and Evolutionary Biology.

Looking to today, it’s only possible to see the southwestern terrapin in a few isolated locations in LA County — and it’s a candidate for listing in the US Endangered Species Act, along with the closely related northwestern terrapin, Shaffer said.

“If we don’t do anything, they will go away,” Rosi Dagit, a senior conservation biologist in the Santa Monica Mountains Resource Conservation District, said via email. “Our turtles have unique genetic traits that preserve biodiversity.”

If LA County’s native turtles are endangered, the future of the Southwest’s terrapin species could be in jeopardy. Eventually, if too many animal species disappear, the Earth’s ecosystems could become unbalanced.

So where have our native turtles gone? And how did the non-native turtles get here?

Generally speaking, “The turtles that we see in pretty much every city park pond are turtles that were once someone’s pet and then were abandoned. Or they’re the offspring of abandoned pets,” said Greg Pauly, curator of herpetology and director of the Urban Nature Research Center at the Natural History Museum of Los Angeles County. “That covers about 99.9% of the turtles in urban park ponds in that area.”

“The turtles that do well are a few species of non-native turtles, and the most important one is the red-eared slider,” Shaffer said.

Red-eared sliders are “beautiful, especially when they are babies.” But they don’t stay small forever, as some adult turtles grow to almost a foot in length — prompting many people to make their adult turtles “back home” by releasing them in urban ponds and lakes.

It’s illegal to release turtles — or any other aquatic plant or animal — into California waters. But the damage is done – in California and far beyond.

“They’re in Europe, they’re all over the United States, they’re in South America, they’re in Australia [and beyond]’ said Schaffer. “They are now self-breeding in many parts of the world, including in Southern California.”

How did a reptile native to the Mississippi Valley spread so far across California?

“One of their keys to success is that they’re a real generalist species,” Shaffer said. “They will eat almost anything” and can nest in “a whole variety of different places” — including parks and other public spaces in Los Angeles. If a sprinkler turns on and the eggs get wet, the egg may survive—unlike the eggs of native southern California terrapins.

“You’re just built to be around people,” Shaffer said.

But despite their adaptability and high population numbers, life is far from perfect for red-eared sliders that inhabit LA’s urban ponds and lakes.

“There’s a lot of competition for food, there’s competition for places to sunbathe,” Pauly said. “You’ll see scars on some of the females that are just constantly being molested by the males.”

“Many [turtles in L.A. ponds and lakes] are sick, many of them have fish hooks in them,” added Robert Fisher, a senior research biologist at the US Geological Survey’s Western Ecological Research Center.

Additionally, red turtles that were born and raised in captivity for part of their lives now have skeletal problems and carapace deformities due to “inadequate care,” Pauly said.

“I have a hard time seeing a city park pond full of turtles without feeling a little depressed,” he added.

The threats that red-eared sliders face — including being hit by a car, or being attacked by a dog or raccoon — the native southwestern pond turtle would face similarly if it ever revived in Los Angeles (actually, cars , Dogs). and raccoons are already a threat to southwestern terrapins in urban wildland areas).

Southwestern terrapins are too forced to compete with red-eared sliders to eat, Pauly added.

Drought, flooding and wildfires threaten the future of the Southwestern terrapin. “Among the top five threats to [southwestern pond turtles]most impacts are linked to and possibly caused by climate change,” he concluded a work published last year in the Journal of Fish and Wildlife Management.

The numbers paint a bleak picture.

In 1986, the Southwestern Herpetologists Society documented the occurrence of western pond turtles at 30 locations in the Santa Monica Mountains, Dagit said. “In 2009, we found turtles at eight of those 30 sites.”

If Angelenos wants native tortoises to thrive, things need to change, experts say.

Southwestern terrapins need water to survive. “They don’t eat when they’re on land. And they don’t breed or mate when they’re on land,” Dagit said. “As a result of the drought of the last 10 years, our turtle populations have been really hammered.”

Last September, Dagit came up with the idea of ​​”running hoses 2,000 linear feet over a height of over 200 feet to bring water to some remote refugio pools that we know support the turtles because they stay in the water the longest.” keep”.

“We thought if we could help keep water in those two tanks, we’d give the turtles a little extra opportunity to feed and mate even when everything else dries up,” she explained. “I had 25 volunteers help carry 2,000 feet of tubing up a very steep, rocky canyon to do a proof of concept. And it worked.”

In May, “we installed a more reliable system,” Dagit said, “and were able to keep water levels in the tanks high enough to support summer feeding and mating.”

Water is a tricky business for Southern California’s native turtles. On the one hand, it is necessary – and on the other hand, artificial ponds, lakes and reservoirs have allowed non-native species to thrive.

“In the past, year-round ponds and lakes were uncommon in California because of our long, dry summers. Native terrapins have evolved in this climate and can survive this long dry spell,” Pauly explained via email. “With the permanent water, folks [and often government agencies] introduced non-native fish such as bass and sunfish, as well as non-native bullfrogs. The fish and bullfrogs then eat our resident turtles. The red-eared slider was also able to establish itself, as it also needs water all the time.”

Pauly’s proposed solution: “If we manage water resources so that they occasionally run dry, we can exclude many of these non-native predatory species, thereby also helping our native terrapins, native frogs, and many other species.”

This strategy can be very effective, especially when capturing native turtles and keeping them appropriate while removing the invasive species, Dagit added.

Southwestern terrapins also respond well to vegetation around bodies of water. It would be beneficial to grow plants around lakes and ponds like those seen in the Ballona Wetlands, Shaffer suggested. Park fences to deter turtles from roaming roads and away from dogs that might bite the reptiles would also help.

These steps “can be difficult to accomplish,” Shaffer said, “but they are doable if there is a will.”

Californians can help turtles in many ways. If you’re hiking and see one on a trail, let it be — some well-meaning hikers assume turtles have been lost and take them out of their habitat to a wildlife center, Fisher said.

Safe driving in turtle habitats is also important, he continued.

And if you buy a turtle from a pet store and decide you can’t keep it, don’t release it into a pond, lake or other waterway, Fisher said. “Bring it back to the pet store you got it from.” California wildlife: Why are so many turtles in LA parks?

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