STUDYING A DIFFERENT BIBLE
This issue was originally published in the May 31, 2025 Editon
Countless books have celebrated Yosemite National Park’s scenery, geology, and trails. But until now, just one has solely chronicled the Park’s wildlife.
In 1924, pioneering field biologist Joseph Grinnell published the first comprehensive study of Yosemite’s animal life. Now, 100 years later, wildlife advocate and author Beth Pratt is releasing a modern follow-up built on Grinnell’s legacy and her decades of research.
“Grinnell had the foresight to say, ‘The biggest value of animal life in Yosemite isn’t going to be realized until 100 years later.’ And he was right,” Pratt said Tuesday evening during a lecture at the Sierra Nevada Aquatic Research Laboratory’s Page Center.
Pratt, the California Regional Executive Director for the National Wildlife Federation and author of When Mountain Lions Are Neighbors, calls Yosemite her favorite place on Earth. Grinnell’s book, she said, is her “Bible.”
Her upcoming book, set for release in October, builds on Grinnell’s original work and a major 2007 resurvey by UC Berkeley and the National Park Service, which retraced the original expedition’s steps. By comparing the two studies, Pratt said, researchers can now uncover how Yosemite’s wildlife is responding to a century of environmental change.
“You can take a photo from the 1915 survey and compare it to one from today,” Pratt said. “Now we can track how the climate is changing, how wildlife is shifting, how flora and fauna are responding.”
Pratt’s new book doesn’t attempt to document every animal in the Park. Instead, it focuses on those species whose lives are deeply intertwined with Yosemite’s landscape.
“I don’t know if there is another park that has this, and especially with the environmental challenges we’re facing, this has become even more critical,” she said.
Pratt paired her enthusiasm for Yosemite’s wildlife with a 161-slide deck, and she only had time to highlight just a few of the creatures featured in her book.
Among them was the elusive Lyle Mountain Salamander, a species with no close relatives in North America.
“They’re a biogeographic mystery,” Pratt said. “You’d have to go to Europe tofind anything like them. How did they end up on Mount Lyell and at the top ofHalDome? Probably something to do with glaciation, but we still don’t know.”
Even more amazing, the salamanders have adapted to their environment. They use their thick tails like walking sticks and can curl into a ball to protect themselves from predators or rockslides.
Another mysterious Yosemite resident, the Mount Lyell Shrew, was first known only from dead specimens collected by Grinnell.
But recently, three researchers successfully trapped and photographed a shrew safely near Lee Vining.
The researchers had to feed the shrew every two hours to keep them alive, and they discovered that the tiny creature liked to cuddle.
Pratt also outlined one of her favorite species in Yosemite: butterflies. There are over 60 species of butterflies that spend part or all of their life cycle in the alpine zone at 11,000 feet and higher.
She showed a video of one of her favorite spots, which she called Butterfly Hill, where there seemed to be thousands of butterflies fluttering around.
Among them, she said, were alpine swallowtails, Sierra Nevada checker spots, and rockslide sulphurs, found nowhere else in the world.
But, with climate change, she worries the populations are in decline, like the California tortoiseshell.
“I haven’t seen a big migration in 10 years,” she said.
Pratt’s favorite animal, though, is the pika, a small, rabbit-like mammal that thrives at high altitudes.
Grinnell observed that pikas howl at the moon, which Pratt said wouldn’t surprise her.
“For those of you who’ve seen them in the wild, they’re like little dogs – they have a sense of their toughness outside of their size,” she said.
Pikas don’t hibernate and instead spend all summer gathering food and storing it in elaborate hay piles. Like people, they have different preferences on what they eat and store various things in their hay piles.
There were a lot of cute pika pictures and videos in the slideshow, and Pratt even showed a collage of their butts, which she exclaimed were just “too cute.” The audience was on board, and then she said their poop was cute too. Fewer people seemed to agree.
But, fascinating enough, because Pikas tend to poop in the same place each time, their latrines make for excellent carbon dating tools.
Evidence shows that Pikas are moving further north with global warming, and, Pratt said, this means we probably are not going to have Pikas in the Sierra in the next century.
The disappointing truth is that while Yosemite’s wildlife is impressive and beautiful, it’s at risk. Studying populations over time provides researchers with unique insights into what is happening to the Park’s ecosystems, helping them forecast what is likely to happen.
