A long shot that anyone can advise me

I’ve no advice on your visitor but how about setting up one of those motion activated cameras to catch the culprit?

My Saturday night brain just thought:

“Half a pound of tuppenny rice,
Half a pound of treacle.
That’s the way the money goes,
Pop! Goes the weasel.”
🎵 🎶

Sorry. 😁
Hope you get more intelligent responses soon MOnica!

Squirrels love hazelnuts.

Pine Martens eat nuts and will often find a cavity in a building for a nest.

Stone Martin (fouine) are renowned in France for inhabiting loft space, they’ll venture out if undisturbed.

growstuff squirrels, like mice bore holes in nut shells, we had a huge hazel tree in our garden in England 25 years. We never got a single nut off it. The squirrels got everyone and neatly bored holes into all of them.

The shells in our house are being shredded, also we do not have squirrels in the area and it is unlikely they could get from the loft into the rest of the house, and visit the bedrooms, but not go downstairs.

Sago I doubt pine martens would be running round our house, according to google they are the size of a domestic cat and would probably leave sizeable heaps of poo. Whatever it is is likely to be mouse or weasel sized.

We have mice in the house every year or so, so we are well accusntomed to them and this is why we know whatever 'it' is, it isn't a mouse.

We live in Nouvelle Aquitaine and have had pine martens in the loft or could be squirrels. A camera seems like the best idea to give you an idea of what you are dealing with
Good luck.

My bet would be pine marten. I saw a video clip of one in a house stealing bread and jam off a table! They can squeeze through pretty small spaces. The neighbour might have mistaken a weasel for pine marten.

The only thing I can suggest is that you set up an infra red camera and ask your concierge to check it and reset it. That might show you who your visitor is. We use one in our garden to check on the resident hedgehog. It also showed us that we had a more unwelcome visitor - a rat, which we are now in the process of dealing with,

Just found this MOnica.
You mentioned mice did you mean this sort?

ptes.org/wp-content/uploads/2019/04/Help_us_find_hazel_dormice_generic.pdf

I had a weasel in my living room that the cat brought in. The cat then had the sense to keep away from it. It had a very distinctive smell. I managed to get it into a bucket and carried it to a nearby field to release it. Instead of running away it came straight for me. Feisty little so and so!

growstuff

Squirrels love hazelnuts.

My first thought was a squirrel.

Our neighbour where we lived previously had squirrels in her loft and we had one that somehow got into the cavity walls, it was peering at me through the air vent in the kitchen wall. Presumably it left the same way it got in.

Dormice and voles will make a round hole in the nut, squirrels will crack it open neatly, but don't usually shatter the shell.

Weasels eat small mammals and birds.
Woodpeckers will smash it but I think you'd notice one of those in the bedroom.

Maywalk

Just found this MOnica.
You mentioned mice did you mean this sort?

ptes.org/wp-content/uploads/2019/04/Help_us_find_hazel_dormice_generic.pdf

Yes, could be a hazel dormouse.

There's a picture in the link of nuts eaten by a dormouse.

I love uour link Maywalk

We stayed in a holiday house inNormandy a few years ago and we’re disturbed by something careering around partying in the the loft every night. I spoke to the owner and she said it was probably a Stone Martin. They can do quite a lot of damage apparently and they get in through gaps in the eaves so I would check out the loft and block the holes if possible.

My mother-in-law had squirrels making a mess with Christmas Nuts one year. Took ages to find them. After a fire it was discovered they had come in down the chimney. There were footprints.

No, the mice are traditional house mice, we seem to get them in about every three or four years and they eat the packets of mice poison I lay. They come in via the downstairs and are mainly confined to the kitchen.

The very distinctive feature, in fact only identifiable feature of the unknown animal is that it shreds hazel shells, no holes, no cracking open but shredding with the run of the fibre of the shell from base to apex - and no pellets that we can find, neither the little trails of mice pellets or any other.

Apart from the shredded hazel shells, left in corners of the bedrooms and bathrooms, and once, in a closed drawer it leaves no other signs. It ignores the packets of poisoned seeds we leave out for the mice.

If the animal is coming from the attic, which is likely, it needs to get past a close fitting door with a solid draft excluder pressed against it.

I think it is going to be quite small, similar in size to a mouse or weasel.

I do not think anyone would confuse a weasel and a marten of any kind. A weasel is about 20cm long and weighs at most 100grms (8 inches, 4oz) while the maretns seem to be around 40 cm long, tall, and weigh up to 2 kilos (16inches, 4lbs)

NotSpaghetti

My mother-in-law had squirrels making a mess with Christmas Nuts one year. Took ages to find them. After a fire it was discovered they had come in down the chimney. There were footprints.

😂😂😂
It wouldnt have been funny of course
Are you sure they weren't reindeer?

Ha ha Callistemon21
Maybe.... but the footprints were rather small!