I made a small rearrangement in the room and now the dogs had to choose new places to sleep.
Stepan chose a special bed for dogs and he is very jealous of it. If someone tries to take his place, he stands nearby and barks until the invader leaves.
The only one Stepan lets in his place is Bucks. I think Stepan takes pity on him. Bucks came to us later than Stepan. He was hungry and unhappy. The rest of the dogs appeared in our home earlier and Stepan, apparently, thinks that they have always been pets and have never wandered or starved.