Saving western pond turtles at the San Francisco Zoo

Host: Over the past 150 years, humans have shrunk the West Coast’s wetland habitats, introduced invasive species and exploited animals. This has taken a toll on the region’s only native freshwater turtle—western pond turtles. Today, the San Francisco Zoo helps give these reptiles a fighting chance by raising hatchling western pond turtles until they’re big enough to survive on their own. 

Here’s KSQD science reporting intern McKenzie Prillaman with the story.

The San Francisco Zoo has all sorts of animals on display… lions, koalas, lemurs.

But the zoo also cares for animals hidden from the public eye… like western pond turtles.

I’m McKenzie Prillaman, a science reporting intern at KSQD.

Western pond turtle are the West Coast’s only native freshwater turtle. And these shy reptiles – about the size of your hand – might be hiding in your own backyard.

Jessie Bushell: I do have to say I have fallen in love with this turtle. (laughs)

That’s Jessie Bushell. She’s the director of conservation at the San Francisco Zoo. For almost two decades, she’s led the institution’s efforts to raise hatchling western pond turtles.

The zoo does this because these turtles are in trouble. They might even be named a federally endangered species in 2023.

That’s because humans and climate change are shrinking their wetland habitat. And Invasive species also threaten their livelihood.

Jessie Bushell: They’re getting pushed out by people’s introduced pets…people dump their turtles, those turtles may be bigger, more aggressive, introduce disease to our native turtles pushing them out. Bullfrogs – they’ve documented tons of bullfrogs with baby turtles in their mouths. 

The zoo takes care of hatchlings until they’re bigger than a bullfrog’s mouth, about two years old, before releasing them into the wild. In other words, Bushell and her team give these turtles a head start.

It all started with a phone call from Sonoma State University.

A biologist there wanted to study how western pond turtles develop. That’s because they, like many other reptiles, have a unique feature: The egg’s temperature in the nest determines if the hatchling will be a male or female.

But conducting this experiment meant there would be a bunch of baby turtles with nowhere to go. So, the San Francisco Zoo got involved.

Jessie Bushell: And so he reached out to us to see if we would headstart those turtles so that we could release them back to where he was collecting them from. 

The zoo didn’t have a conservation program at the time. But with the help of many supportive partners over the years, Bushell and her team have raised and released nearly 400 western pond turtles in central California.

Jessie Bushell: So going from like this one call that started this little a little project with…50 or 60 turtles, almost 20 years ago, we’ve now had this huge, really intricate and really expansive collaboration. 

One place where the zoo released turtles is the Presidio of San Francisco. It’s a former military-base-turned-national-park at the city’s northern edge. And it provides a little natural refuge within the bustling metropolis.

But the Presidio wasn’t always this way.

Jonathan Young: So this would have looked way different 20 years ago, like unrecognizable.

That’s Jonathan Young. He’s a wildlife ecologist at the Presidio. And he’s helping to revive the park’s wetlands.

One way the Presidio has done this is by restoring a small body of water called Mountain Lake at the south end of the park. It was filled with invasive species and contaminated by runoff from Highway 1.

When they finished reviving the lake, the Presidio wanted to bring back native species… that included western pond turtles.

So in 2015, the San Francisco Zoo released 55 young turtles into the lake.

Now, Young is finally seeing all this hard work pay off.

On one sunny day last April, he…

Jonathan Young: just saw leaf that moved ahead. And I was like, wait a minute, that’s not a leaf.

It was a baby western pond turtle. And after looking around on the shore, Young found a bunch of shell fragments from freshly-emerged hatchlings.

These signs point to a new generation of turtles, indicating the Presidio’s western pond turtle population can sustain itself.

Thanks to the San Francisco Zoo and its collaborators at the Presidio, Yosemite the Marin Headlands and other places, western pond turtles still have a shot at surviving for many years to come.

 This is McKenzie Prillaman, a science reporting intern at KSQD.