Common hamster: Threatened with extinction across its entire range

The increasingly rare common hamster is now officially threatened with extinction across its entire range. This is the finding of the new Red List of Threatened Species published by the International Union for Conservation of Nature (IUCN) Lemur species and a right whale in the Atlantic have also been newly listed as threatened with extinction, as the IUCN reported on Thursday in Gland, near Geneva.

Within the European Union, the common hamster (Cricetus cricetus) is already strictly protected, but the IUCN had not previously classified it as endangered at all, due to a lack of survey data. Conservationists had assumed that large numbers of the endearing-looking rodents still existed in Eastern Europe and Russia.

That assumption was wrong. “If nothing changes, the common hamster will be extinct within the next 30 years,” the IUCN now warns. Common hamsters once lived in their millions across the region stretching from Alsace to the Yenisei River in Siberia. For farmers, these “architects beneath the fields” were a pest, tunnelling under farmland and consuming harvests. Bounties were paid for every hamster killed in order to control the plague. Since then, much has changed: “There are estimates that the population has declined by 99 percent since the 1950s.” The species extinction crisis has long since come to affect even species once thought to be common.

Hamsters are having fewer young

It is suspected that the vast monocultures covering agricultural land are taking a toll on the animals. Harvests are also carried out faster than in the past, stripping hamsters of their habitat taken. Many farmers have long since become hamster-friendly, says Monecke. For 20 years, strips of wild plants have been left between fields or harvesting has been delayed. While this has slowed the decline, it has not been able to stop it so far.

The specialist, who focuses on chronobiology — the timing of physiological processes and recurring behavioral patterns — suspects other problems are at play. She has found that common hamsters have been producing fewer young since the 1950s. There are fewer litters per year with fewer offspring. In 1954, the average was still nine young per litter; by 2015, it was just 3.4.

Light pollution could be one cause, Monecke believes. Hamsters have an internal clock that controls when they stop reproducing in summer and when they wake from hibernation. This clock is calibrated in summer, and for that, precise perception of sunset is necessary. Artificial light sources could blur this signal. Too little light could also generate a false cue.

«When the combine harvester comes and strips the field bare within a few hours, the hamster retreats into its burrow and sits in complete darkness,» she says. For the hamster's internal clock, this means — partly because mowing already takes place in June or July due to climate change — that it is now winter. There is a paradox: the earlier the hamster switches to winter mode, the later it begins reproducing the following year and the fewer young it produces.

Why we need common hamsters

Why does the world need common hamsters? «They are embedded in an enormous food chain,» says Monecke. Birds of prey that can no longer find hamsters would have to hunt smaller rodents, flying out more frequently as a result, which in turn disrupts their own lives. With the new IUCN classification, Monecke hopes for new research funding to systematically investigate the causes of their disappearance and, above all, the puzzling decline in their reproduction rate.

The European Court of Justice strengthened the right of European hamsters to their habitat at the beginning of July. Their burrows may not be destroyed even if the animals are not currently using them but might return to them. The background was a case in Austria where hamster burrows had been destroyed for a road. In May, the environmental association Bund Naturschutz Bayern filed a complaint with the EU Commission because, in its view, Bavaria had not taken effective measures to prevent extinction.

These animals are also at risk

The IUCN also reclassified 13 lemur species as more endangered. 103 of the 107 lemur species are now threatened with extinction due to deforestation and hobby hunting in Madagascar. Among them is Madame Berthe's mouse lemur (Microcebus berthae), the world's smallest primate, with a body length of just around ten centimetres. The North Atlantic right whale (Eubalaena glacialis) is also newly classified as threatened with extinction. In 2018, estimates put the remaining population at just 250 individuals.

The whales followed prey that were moving northward due to higher ocean temperatures. There, they became more frequently entangled in fishing nets or were injured by boats.

In total, the Red List — maintained since 1964 — now includes just over 120,000 animal and plant species (previously: just over 116,000). The list is updated at least once a year. More than 32,000 species are currently threatened with extinction — species that, in the IUCN's view, will not survive without conservation measures. They are divided into three categories: “vulnerable,” “endangered,” and “critically endangered.” In this highest category, including the European hamster, there are now 6,811 species (previously 6,523). (SDA)