Scientists Are Learning A Lot About Los Angeles Lizards | KCET
Scientists Are Learning A Lot About Los Angeles Lizards
It's a few minutes before 8:00 a.m. The sun is low on the horizon, barely lighting up the oak-dotted canyons of Point Mugu State Park. The grey of the marine layer blends seamlessly into the sky, just barely transitioning into its familiar blue. The scrub jays have been flitting about for a while, and the crows are already hollering. In the distance you can make out the faint hum of early morning traffic. The repetitive lapping of the waves against the shore is just loud enough to notice. The coffee hasn't had quite enough time to kick in, but Seana Leary is already shoulder-deep in a bucket of lizards.
Leary is part of a team of interns with the National Park Service's Santa Monica Mountains National Recreation Area. Each morning, they fan out from the park service's headquarters in Thousand Oaks and disperse across the range.
Dozens of buried buckets and other kinds of humane traps are scattered across the mountains, most of them set far enough back from hiking trails and dusty fire roads that nobody would notice. Each morning, the interns set about seeing what's gotten caught in those traps since they were emptied the previous morning. While interns come and go every six months or so, the park service has conducted this long-term monitoring effort for nearly seventeen years, since 2000.
NPS wildlife ecologist Katy Delaney, who oversees the study, says that the goal is to see "what we have, where we have it, and how the populations are doing." Each animal caught in the buckets – not just the lizards and snakes, but also small mammals like shrews and bugs like scorpions – gets recorded on an iPad. The data, which includes the length and weight of the animals, allows researchers to learn not just which animals live in which places, but also how their populations have grown and shrunk over time, something only a long-term study like this one can accomplish.
As far as the more immediate, practical, day-to-day reptile-related concerns that most hikers have, take note: on this random Tuesday in August, Leary pulled side blotched lizards, western fence lizards, and whiptail lizards out of the traps she'd been assigned to monitor, most of them babies, plus a peculiarly sluggish striped racer, a few shrews, lots of beetles, some centipedes, way too many scorpions, and one tarantula. In four months of daily monitoring, she says, she's never even seen a rattlesnake, the only dangerously venomous snake to slither these canyons and hilltops. It's not that they're not present; of course they are. But they're usually clever enough to avoid people, including, it seems, at least one curious herpetologist-in-training.
The last seventeen years have provided an incredible glimpse into the triumphs and struggles that wild animals endure as they make a home for themselves in as strange a landscape as the Santa Monica Mountains, beyond the harassment that harmless snakes get due to our overwhelming fear of the legless critters.
"Our park is so weird," says Delaney. The Santa Monica Mountains are like a patchwork quilt of land scraps, administered in some spots by the National Park Service, and in others by state, city, or county governments. And some properties are privately owned. The mountains are bounded on two sides by freeways, on the third by the Pacific, and on the fourth by agricultural fields. Yosemite or Yellowstone this is not.
While some of the pitfall arrays are set in the wilder parts of the park, others are located in more curious spots. A couple are just steps away from the US-101, one of the world's busiest highways. Another is inside a botanical garden. If there's any park that can demonstrate the ways in which wildlife can survive and even thrive in highly disturbed urban environments, this is it.
It's this blend of developed and wild that allows Delaney to do more with her data than simply keep tabs on the wild reptiles that call Los Angeles home. "Because we have all this habitat fragmentation," she says, "we can look at variables [like] nearness to roads or the size of the habitat patch." How much nearby vegetation does a snake or a lizard need to be happy, and does it matter what kind? Does the presence or absence of a permanent water source affect the abundance or distribution of a species?
And because the interns also collect small biological samples from the animals, Delaney and her colleagues can monitor the flow of genes through a population. Are the lizards in one canyon mating with those in the next canyon over, or are they genetically isolated? If there's no gene flow (and there should be), what is stopping the animals from moving around?
But the last seventeen years have also provided Delaney with two unique points of interest. The first was the Springs Fire, which burned from the 101 freeway near Camarillo all the way to the ocean in May 2013. Since firefighting efforts are typically directed at saving the lives of people and structures, fires are usually allowed to burn through wildlands like Point Mugu.
That allowed Delaney a unique glimpse into how a community of animals can recover after a major, acute trauma like a fire, followed by the ongoing, chronic trauma of drought. "It burned in May, then it rained, and then there were a bunch of mudslides. And then there was a drought," she says.
It's still tough to say just what all this has meant for reptiles, in part because we're still stuck in the fifth year of that ongoing drought, and in part because the pitfall arrays were only deployed in the fire-affected part of Point Mugu for a few months before they burned.
(An example of Delaney's commitment to the animals: two days after the fire swept through, firefighters accompanied Delaney as she went to rescue whatever animals might have survived the fire that had then fallen into the traps so that they wouldn't die of starvation, trapped in a bucket.)
Still, she's got at least a general sense of how the animals are faring, even if the data aren't ready to confirm her observations. And in general, most of the species have recovered since the fire. "It was slow at first, but [now] in the burn area, we are catching a lot of lizards," she says. The salamanders, however, still struggle. That could be because the post-fire landscape is a lot grassier than the pre-fire oak-dominated chaparral, and salamanders rely on oak leaf litter for their habitat.
And then there's the prospect of climate change. "[Reptiles] in general are sensitive to environmental changes," she says. Indeed, even so-called “cold-blooded” animals, like lizards and snakes, can suffer as the Earth's thermostat gets turned up.
"Those are the things that worry me. Common species disappearing is an alarm bell." If a species as common as the western fence lizard, for example, starts to show signs of trouble, it's prudent to find out why. Because when wildlife is in trouble, so are we.
And so Leary will continue to hike, climb, drive, and bushwack through the hillsides to count the lizards and snakes. Despite the tediousness of the ordeal and the occasional run-in with poison oak, she says she loves her job. "I come home tired and hungry and sweaty, but those aren't bad things," she says.
For the record: A previous headline on this piece referred to citizen scientists involved in this program. That wasn't precisely accurate, as the interns involved in this program have scientific training, so we changed it. Our apologies.
For ongoing environmental coverage in March 2017 and afterward, please visit our show Earth Focus, or browse Redefine for historic material.
KCET's award-winning environment news project Redefine ran from July 2012 through February 2017.
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