The framing of the shrew: California students photograph mammal never caught on film

The Guardian

26-01-2025

In a 7,000ft-high marshy spot in the cold, rugged eastern Sierra mountains, two groups of mammals scurried around at night. One was going about their normal nocturnal routine of hunting worms. The other was hoping for a glimpse of an elusive creature: the Mount Lyell shrew, the only known California mammal never photographed alive.
The three young student scientists faced a tight timeline. They baited 150 pitfall traps – small cups dug into the earth to catch wandering creatures – with cat food and mealworms and monitored them across a 600ft area, checking each trap every two hours for any signs of their goal. They slept no more than two hours at a time. Shrews have such a fast metabolism that they die in traps quickly, one of the reasons this species had never been photographed or studied live.
Despite initial skepticism, they caught five shrews within the first 24 hours, working mostly during the night and early morning. They filmed and photographed the tiny creatures, and clipped tiny flaps of skin from the animals' ears for genetic testing later to confirm they'd caught the right species.
When he held one, Prakrit Jain, a 20-year-old student at University of California, Berkeley, and intern at the California Academy of Sciences, noticed how remarkably small and light the animals were. Less than 4in long, the lightest shrew was just a gram-and-a-half – about the weight of two paper clips. 'It was very different from holding a mouse or a hamster,' he says. 'These shrews are almost the size of an insect.'
First described a century ago, the tiny burrowing animal hadn't been seen in 20 years – and virtually nothing was known about it. The Mount Lyell shrew lives in a small range in the high Sierra Nevadas, and is considered a species of special concern, due to threats from the climate crisis to their high-altitude homes. But there have been no field studies of the animals, and the only specimens ever gathered have been dead.
'It was kind of a crazy idea,' says Vishal Subramnyan, a student at UC Berkeley and a content creator at the California Academy of Sciences. 'California is one of the most well-studied places in the world, and yet there's a mammal species in California that's never been photographed alive. That was shocking to us.'
The 22-year-old teamed up with Jain and his friend Harper Forbes, 22, a student at the University of Arizona. With only a month before the snows arrived in the winter, they had to move fast to put together an expedition. The group received a permit from California's department of fish and wildlife and headed east from the Berkeley campus in early November. (As high schoolers, Jain and Forbes had previously discovered two new-to-science scorpions in the Bay Area.)
Having photos and video of the shrew helps scientists know more about the species – and can help efforts to conserve it. Mammal specimens are often studied as skin or skeleton, or a whole animal preserved in alcohol. While those are useful to preserve animals for future study, they don't capture the way the animal appears in real life – because the skin loses its shape, and the preserved specimens in alcohol lose the color. 'Because we were able to get good photos of a few of these species, it becomes easier to identify these things in the field,' says Jain.
Shrews are a group of species that are very overlooked, but there's an extraordinary diversity within the group, Jain says. 'Many, many species of shrew are known from only a single specimen, or only known from a single locality, or have not been seen in decades,' he says. 'So if we struggle to find a shrew in a place like California – one of the best studied places in the world – you can only imagine how the shrew diversity of places like south-east Asia and central Africa, for instance, can just be so under-appreciated.'
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Because they have such a high metabolism, shrews eat nearly constantly. They can consume their body weight or more of insects every single day – meaning in their habitats, they can have a big impact on small insects. 'There's few other animals I can think of in the ecosystems where shrews live that have a similarly high impact on the insect numbers simply just by consuming them,' Jain says.
As the climate warms, the animals are squeezed into a smaller area to maintain their habitat. The shrew probably arrived in California during the last ice age, and as the ice receded it settled into a high mountain area. But studies estimate that 50% to 90% of the Mount Lyell shrew's habitat will disappear by 2080 – putting the species in serious danger. They are also eaten by larger nocturnal predators such as owls, hawks, snakes and weasels.
Photos can not only catalog biodiversity in a rapidly changing planet, they can also help the public understand and foster a connection with an animal. 'If we look at the extinction crisis and the types of animals it's impacting, a lot of animals are disappearing without any documentation,' says Subramnyan. 'An animal like the Mount Lyell shrew, if it was not photographed or researched, could have just quietly disappeared due to climate change, and we'd have no idea about it at all.'