On November 20, 2016, the most powerful particle accelerator ever built stopped working. The Large Hadron Collider, a seventeen-mile ring of magnets under the French-Swiss border, lost power completely. Engineers found a small brown animal dead next to an 18,000-volt transformer it had climbed onto. It was a stone marten, and its body is now on display at the Natural History Museum in Rotterdam. It wasn’t even the first: on April 28, 2016, another stone marten shorted out a 66,000-volt transformer at the same facility.
Martens at a glance
- Genus Martes, in the weasel family (Mustelidae)
- Species 7 or 8, all in the Northern Hemisphere
- American marten 19 to 25 in long, up to about 4 lb
- Diet Mostly small rodents, plus berries
- Rarest Nilgiri marten, about 1,000 adults
What is a marten?
Martens belong to the genus Martes, alongside weasels, otters, badgers and wolverines in the family Mustelidae. Species include the American marten, European pine marten, beech (stone) marten, sable, yellow-throated marten and the Nilgiri marten of southern India. Every one lives in the Northern Hemisphere; none has ever established a wild population anywhere else.
The body is long, low and narrow, with a bushy tail about a third of its length. The feet are oversized, and in winter long hairs grow between the toe pads to create natural snowshoes, letting a marten run across powder or tunnel under the snowpack to hunt.
Diet
In Alaska, American martens live mostly on voles, and marten numbers rise and fall with vole numbers. In autumn, pine martens studied in Scotland and on Minorca took up to 30 percent of their diet from berries, while martens in Poland ate almost no fruit at all.
An eight-month pregnancy that’s really one month
A female pine marten mates in July or August, and then nothing happens. The fertilized egg floats unimplanted for about seven months until lengthening daylight in late February and March triggers implantation. Development then takes 30 to 35 days.
Five very different martens
- Sable: the densest fur in the genus drove Russian expansion across Siberia. At the trade’s 17th-century peak, furs made up about 20 percent of the Russian state budget, and one sable skin was officially worth 16 polar fox pelts or 100 squirrels. Wild sable number about 1.2 million.
- Beech marten: adapted to towns, attics and engine bays. Germany reports more than 200,000 cases of marten damage to vehicles a year. A marten scent-marks a warm engine, the car moves, a rival finds the scent and attacks the cables carrying it.
- Yellow-throated marten: hunts in groups, usually siblings, taking musk deer, young roe deer and rhesus macaques many times its weight.
- Nilgiri marten: confined to India’s Western Ghats with about 1,000 mature individuals, the only species in the genus listed as Vulnerable.
Saving the red squirrel
In Britain and Ireland, martens solved a problem nobody expected. In 2014, Emma Sheehy and Colin Lawton showed that as pine martens recovered in Ireland, invasive gray squirrels vanished and native red squirrels returned. Sheehy and Xavier Lambin confirmed the pattern in Scotland in 2018. Gray squirrels, from North America, have no evolved defense against a marten. Red squirrels, which have shared forests with them for tens of thousands of years, do.
That changed policy. Pine martens were released in mid-Wales in 2015 and the Forest of Dean in 2019. Fifteen went to Dartmoor in September 2024 and nineteen to Exmoor in October 2025, the first attempt to restore the species to southwest England since it was wiped out there in the 1880s. Kits were filmed on Dartmoor in June 2025.
The takeaway
Martens need old forest with fallen logs, hollow trees and heavy canopy, so biologists use them as an indicator species. Where martens do well, the forest around them is usually intact.
