Stone Marten in the Loft: Signs, Damage and Solutions

About the Stone Marten

The stone marten (Martes foina), also known as the beech marten or house marten, is a small carnivore of the mustelid family — related to weasels and ferrets. Adults weigh between 1.5 and 2.5 kg and measure around 40–55 cm in body length, with a distinctive white bib on the throat and chest. They are nocturnal and extremely agile, capable of squeezing through gaps as small as 6 cm.

Unlike truly rural wildlife, the stone marten is well adapted to suburban and urban environments throughout French-speaking Switzerland. It readily exploits buildings for shelter, warmth, and as a safe location to raise its young. Attics, roof spaces, and the engine compartments of parked vehicles are among its favourite spots.

How to Tell If You Have a Stone Marten

Stone martens are most active between dusk and dawn. The following signs suggest one has taken up residence in or around your property:

• Noises at night: Thumping, scratching, and rolling sounds from the attic or ceiling, most intense between midnight and 4 am. Martens are significantly heavier than rodents, so the sounds tend to be louder and more erratic.
• Strong, musky odour: Stone martens scent-mark their territory with gland secretions and urine. A persistent, pungent smell from the roof space or garage is a reliable indicator.
• Droppings: Marten droppings are elongated, twisted, and contain fur, feathers, fruit seeds, and insect remains. They are typically 8–12 cm long and left in prominent locations as territorial markers.
• Footprints and tracks: Five-toed paw prints (roughly 4 cm wide) in dust, mud, or snow around the building's perimeter and on the roof.
• Damage to insulation: Torn, flattened, or soiled roof insulation where the animal has nested or used as a latrine area.
• Vehicle damage: If your car is parked outdoors overnight, look for chewed rubber hoses, coolant pipes, ignition cables, or fuel lines — stone martens are notorious for chewing vehicle engine components.

What Damage Can a Stone Marten Cause?

Do not underestimate the destructive potential of a stone marten in your property. Left unaddressed, the consequences can be costly:

Professional Exclusion Solutions

In Switzerland, the stone marten is a protected species under the Federal Hunting Act (LChP) and may not be killed by homeowners without a specific cantonal permit. This means lethal trapping is not a standard option, and the only legally compliant approach is exclusion: preventing the animal from entering or returning to the property.

Our approach to stone marten exclusion involves the following steps:

It is important to act promptly. A stone marten that has established a regular presence in your attic will return repeatedly — and may introduce young during spring and summer, making exclusion more complex. The sooner a professional intervenes, the simpler and less costly the solution will be.