With their round cheeks, probing little paws, and fuzzy bodies that fit perfectly in your palm, domesticated hamsters are popular pets. But lesser known are the 26 species of wild hamster that scamper through parts of Europe, Asia, and the Middle East—all of them cute, but not necessarily cuddly.
The aggressive European hamster, for instance, will leap at and bite any person that tries to touch it, says Mikhail Rusin, a researcher at the Kyiv Zoo in Ukraine. “Even those born in captivity, when they grow up, are not tame,” he says.
Ferocious as it is, this one-pound rodent can’t hold its own against threats such as climate change, agriculture, and light pollution. Those forces likely have contributed to wild hamster population declines, which recently prompted the International Union for Conservation of Nature to designate the species as critically endangered. (Read about the surprising origins of your pet hamster.)
Once found burrowing through grasslands across Europe and western Asia, the hamsters’ range has shrunk dramatically. It’s down by 94 percent in France—where the range now is limited to the Alsace region—and more than 75 percent in Eastern Europe, particularly Ukraine and Russia. Without action, the hamster will go extinct within three decades, according to the IUCN.
The species’ more dire status will likely spur new conservation efforts, says Rusin, an author of the new IUCN listing. He and his colleagues are already doing their part: This week, they reintroduced 11 captive-raised hamsters into the wild in Khotyn National Park, Ukraine, for the first time ever in the country.
European hamsters are important to conserve because they’re a keystone species, serving as critical prey for a host of predators from European red fox to large birds like the Eurasian eagle owl.
“If we lose this species, the ecosystem could collapse,” Rusin says—and that in turn could harm human communities that rely on the environment for food, water, and other services. “Some people think they’re disconnected with nature, but they’re not.”
The species’ extinction would also make the world less colorful, Rusin adds. Its black belly, white splotches, and chestnut back make the hamster “perhaps one of the most beautiful rodents in Europe.”
A complex web of threats
European hamsters evolved to live fast: They come into the world after 18-day pregnancies, and their life spans are short, about two years. But over the last century or so, the hamster’s reproductive rates and life spans have fallen significantly. Females that averaged 20 offspring a year during most of the 20th century now birth only five to six, and the average life span that’s now around two years once was triple that.
The reason for these declines is unclear. It’s likely a combination of factors, including the expansion of monoculture—the practice of planting exclusively one crop, usually wheat or corn—throughout Europe.
As grassland dwellers, hamsters live mostly on farmlands and feed on the crops. But corn or wheat alone is a nutritionally poor diet that can cause health issues, such as protein and vitamin b3 deficiencies. A lack of b3, for example, can lead to abnormal behavior in mother European hamsters such as infanticide, says Caroline Habold, an ecophysiologist at the CNRS-University of Strasbourg. And a lack of protein in wheat-eating mothers’ milk can stunt her pups’ development. In addition, when farmers harvest their land, the hamsters are suddenly deprived of food and more vulnerable to predators.
Warmer, wetter winters due to global climate change are also detrimental to the species. In winter, these hibernators burrow holes more than six feet deep, where they snuggle up warm and insulated by the snow cover. Without this blanket of snow, they’re more exposed to the elements, such as cold temperatures and rain, both of which can kill the animals outright.
One study that Habold co-authored in Alsace suggests that the combination of corn agriculture and an increase in winter rainfall may have caused hamsters’ body weight to decline by up to 21 percent since 1937. Poor body weight is also linked to low fertility.
Another possible factor in the species’ decline is light pollution, which may be disrupting the animals’ circadian rhythms. For instance, while hibernating, hamsters rely on the length of the day to know when to emerge from their burrows. Increasingly, artificial light sources may be blurring those signals, says Stefanie Monecke, a medical psychologist at Ludwig Maximilians University in Munich. (Learn how light pollution is harming ecosystems worldwide.)
Monecke emphasizes that the impacts of light pollution and climate change on European hamsters “are all just hypotheses, but everything points in that direction.”
Fortunately, European hamsters breed well in captivity, Rusin says: There are programs in Belgium, France, Poland, Germany, and Ukraine, among others.
The harder part, he says, is reintroducing hamsters that are not adapted to the wild and are easily snapped up by predators. Erecting fences or nets around their new habitat for a few months can protect them while they acclimate, he says.
Some scientists, such as Habold in the Alsace, are working with farmers to create more hamster-friendly croplands. For example, in smaller plots the main crop may be mixed with another crop, such as protein-rich soy, which is healthier for the hamsters. And farmers may cultivate the margins of these plots with a variety of plants such as sunflower, alfalfa, and rapeseed. Habold also encourages farmers to reduce their frequency of ploughing and pesticide use.
Habold spreads the message that crop diversity is beneficial overall to the health of the farm and the surrounding ecosystem, since many types of plants can support more kinds of wildlife communities, such as pollinators.
“The whole world should think about improving farmland and agricultural practices to restore biodiversity,” she says. “The hamster is only one example.” (Read more about sustainable agriculture.)
Parallels to extinct species
At least in France, conservation initiatives have only stabilized the species’ numbers, not increased them. That’s why the IUCN decision is so vital, Habold says.
The hamster’s listing could also boost research funding into the species’ reproductive failures, which are especially worrisome, Monecke says.
“Think of the passenger pigeon—it was the most abundant bird ever, and it [went] extinct in a hundred years,” she notes. “The problem was they were not able to reproduce anymore, which is quite similar to the hamster. There are so many parallels.”