Marten on and possibly already in the roof

What helped was screwing every second tile down tightly

I had the carpenter here at the beginning of the week. He suggested screwing the tiles along the dormer and putting a rabbit wire underneath. Meanwhile, I have also made quite a bit of progress. I was able to find out with the camera where the marten gets onto the roof. I blocked all access points with pigeon spikes and did the same for the neighbors. The crazy thing was that the marten even jumped into a part of the downpipe where there were no spikes yet (at the bend) and tried to pull itself up there. So I closed that off as well. Meanwhile, we have been marten-free for several days. I hope it was enough to scare it away.

The colleague Msrder was on the roof again for the first time today. That was the first time in over 1 month. Really annoying. He doesn't seem to have made it onto the roof. At least I didn't hear him there. We had it closed up after all. But still annoying. Either he went to the neighbor. We share a roof or he is looking for another opening. I think he somehow got through the spikes or jumped over them. I heard the clinking of the spikes. Now I don't know what else to do. The Machbar now has a balcony power plant. Maybe he also climbed up over the mounting of this.

I am currently researching this as well (still at the very beginning). I have now seen a marten or polecat several times while walking the poodle and have been thinking about how to drive it away. Some neighbors have these ultrasonic devices, the problem is, I can hear them too and they really get on my nerves. Also, I don't know what effects the device has on dogs and cats.
Apparently, dog hair at the spot where the marten likes to get in is supposed to help.

Supposedly, dog hair at the spot where the marten likes to get in helps.

That you see martens from time to time is normal and not yet a problem. It only gets bad when it finds a shelter in your roof.

There are all sorts of tips. Dog urine is certainly better, provided it's a male dog. But that only interests the male martens.
The pest control guy said the most effective thing is to prevent the marten from getting onto the roof. Everything else is not really sustainable. I also wouldn't have thought that mine would jump over barriers made of pigeon spikes. I have to set up the wildlife camera again tonight.