A Waning Rodent Species and Its Connection to the California Drought

Belding's ground squirrel

Belding’s ground squirrels have a surprising role to play in California’s drought. (Photo credit: iStockphoto/Getty Images)

Are Belding’s squirrels heroes or villains? First of all, they hibernate for as long as nine months a year. Second, they are preyed upon by bears, bobcats, coyotes, foxes, badgers, weasels, martens, and various raptors. Third, they’re one of the few mammals that show truly altruistic behavior, warning others in their group of potential threats, even if that means sacrificing themselves. Last but not least, they are undeniably small and cute. So why then is the long-sleeping, widely preyed upon, altruistic, and highly-photogenic Belding’s ground squirrel so despised by farmers in the Sierra Nevada region of California? And why might the species’ potential demise spell disaster for the states residents?

For starters, the squirrel can eat a lot of alfalfa and wheat, completely ruining many staple crops. They often come with fleas, which can carry plague. Perhaps most annoying is that their extensive burrowing can weaken levees, ditch banks, and earthen dams, and undermine the foundations of roadways and buildings. Their burrowing also interferes with natural irrigation patterns, can accelerate soil erosion, and damage farm equipment and livestock who make the mistake running over one. With populations that can reach incredible densities–as high as 100 per acre–farmers do anything they can to curb the squirrels rise, with one claiming I hire high school kids, give them a box of 22s, and a dollar a tail for their efforts.

And the efforts of farmers like the one described above seem to be paying off, with a little help from climate change, because the Belding’s ground squirrel seems headed for extinction. It was a trend noted over a century ago by biologist Joseph Grinnell in his landmark surveys of California species. Grinnell, however, believed deforestation and increased cultivation was to blame. But, when Toni Lyn Morelli, program manager with the Department of Interior Northeast Climate Science Center (based at the University of Massachusetts) went to search for the squirrel in the same areas, she found they had totally vanished in many of them. We were surprised to see such a dramatic decline in this species, Morelli said in a news release about the study. In fact, the rate of decline is much greater than that seen in the same region for the pika, a small mountain-dwelling cousin of the rabbit that has become the poster child for the effects of global warming in the contiguous United States. The decline was most pronounced in those areas that had experienced the highest average temperature rise and most drastic variations in rainfall. Far from alleviating the farmers problems, though, it only prompted more of the squirrels to seek lower-lying, cooler habitats, like the lands used to grow alfalfa.

Decreased snowfall seems to be a major factor in the squirrels plight. It relies on a thick blanket of snow to insulate it during its long period of hibernation. Many probably froze to death without an adequate snow cover, and those that didnt may have drowned when melting snow and rain caused flooding. The squirrels lucky enough to emerge were underweight and not particularly keen on mating. In their weakened state, they also were more susceptible to predators. With the unpredictability of weather seemingly increasing, this trend seems likely only to grow. The farmers should be happy.

The irony is that, while more and more of the Belding’s ground squirrels are moving downhill to munch on alfalfa, the loss of them in their more customary upper habitats is jeopardizing California’s water supply. Belding’s are beneficial to the meadows if, as we suspect, they act as ecosystem engineers and help aerate and otherwise affect the soils of the meadows they specialize in, Morelli told a reporter from Grist, an online environmental magazine. These meadows are then more effective at filtering and holding the water that eventually trickles down, so to speak, to be the water that is drunk and used by the majority of the state of California.”

It seems one of the more distasteful habits of the squirrel, its burrowing, has had heretofore the most unrecognized benefits. According to James Patton, emeritus professor of integrative biology at the University of California-Berkeley, Burrowing animals provide tremendous positive benefit that is completely ignored by everyone, soil restoration being one of them. He adds that their hunger for grasses also is beneficial because it keeps the grasses growing and so helps curb erosion.

For the time being, however, it seems farmers will continue to despise the rodents while their increasing scarcity from their natural habitats will throw the states water crisis into even sharper relief. Apart from that, the plight of the Beldings ground squirrel is another indication of the unforeseen consequences of a shifting climate, as well as a stunning example of how interconnected ecosystems can be and how affecting one can affect many others.

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Comments

  1. This was a fantastic article.

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