Pine martens are helping red squirrels by eating their grey rivals
Where pine martens return, grey squirrels tend to disappear, and red squirrels bounce back. In Ireland the recovering marten has been credited with pushing back the invasive greys. The likely reason is simple: greys spend more time on the ground, while reds evolved alongside martens and know to stay out of reach.
The European pine marten is a weasel-family predator about the length of a small cat, with a body up to 53 centimetres, a bushy tail of around 25 and a weight of about 1.5 kilograms. Its brown fur is short and coarse in summer and long and silky in winter, set off by a creamy yellow bib on the throat. It is the only mustelid with semi-retractable claws, which make it a nimble climber and runner along branches, though it is also quick on the ground.
Mostly active at dusk and night, it eats small mammals, birds, insects, frogs and carrion, and adds berries, eggs, nuts and honey. It marks its territory with black, twisted droppings. Its breeding has an unusual delay: mating happens in July or August, but the fertilised egg waits about seven months before implanting, so the young are born the following spring after only a month of actual pregnancy. Newborns weigh about 30 grams.
People are its main threat, through shooting, poisoning, loss of woodland and trapping for its fine fur. In Britain it was long confined to north-west Scotland and considered extinct in England. That has changed. In 2015 a photographer in Shropshire made the first confirmed English sighting in over a century, and in 2022 a hedgehog monitoring camera recorded the first marten in London for a hundred years. Twenty Scottish martens were released in mid-Wales in 2015, and 35 went into the Forest of Dean between 2019 and 2021, where numbers were nearing 60 by 2023.
In the wild most live three or four years, though one reached 11 and captive animals have hit 18. Croatia values it enough to put it on its euro coins; its old currency, the kuna, was named after the animal, since kuna is the Croatian word for marten.
Source: European pine marten
