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California ground squirrels, usually known for their plant-based diet, have been observed hunting and eating voles in the first recorded instance of the species preying on live vertebrates, according to new research. The study, published in the Journal of Ethology, examines how these squirrels, native to California’s grasslands, adapted to environmental changes, particularly an increase in the local vole population.
In certain parts of northern California, vole infestations have been reported. At the research site, scientists noted increasing vole numbers over the past decade. Traditionally, California ground squirrels are herbivores or granivores, feeding on plants and seeds. However, the new behaviour suggests the species is adapting to its environment by preying on other animals.
“This research radically changes our perception of squirrels, one of the most familiar mammals in the world. In the face of human insults such as climate change and drought, these animals are resilient and have the potential to adapt to live in a changing world,” lead study author Jennifer Smith told CNN.
Smith added that understanding how squirrels adapt to shifts in food availability could provide insights into how other species may respond to changing environments.
Researchers used live traps to catch and release squirrels during the study, which ran from June 10 to July 30. Each squirrel was marked so their movements could be monitored. In 42 per cent of the 74 interactions the team saw between squirrels and voles, the squirrels actively pursued and ate the voles.
“We already knew that (California ground squirrels) could live (in) a range of elevations and feed (on) a breadth of plants but what is most striking and incredible is the speed at which they shifted their behaviour to this local surge in vole abundance,” Smith said.
In addition, the study revealed social dynamics between squirrels and voles not known before. While some interactions were positive, involving foraging, greeting and playing, others were aggressive, with squirrels chasing, biting and pouncing on the voles.
Smith added that these findings could pave the way for future research on how different squirrel species and other mammals adapt to environmental changes. “Animals can either adapt or go extinct in a human-impacted world. These animals are showing us the incredible resilience of some species, and by studying these processes we can offer meaningful insights for conservation,” Smith said.
