Mysterious visitor and molluscan seed dispersal

A quick visit to the Moss early on Tuesday morning and a surprise in the viewing tower. There on one of the landings half way up the stairs was a mess. Most people would say bird poo and move on. But it looked not just any old bird poo but an interesting bird poo. Two big white splashes and a round firm blob (see bottom photo). Something had been spending time in the tower, probably roosting over night. My first though was barn owl as I have seen big white splashes like this left by them before. The firm blob was a pellet of hard to digest bits that birds of prey regurgitate after a day of eating. But a close look at the contents of the pellet, just pick them up and crumble like an oxo cube, and I found it was made up mainly of fur and shiny blue, black bits of beetle. Now barn owl do eat furry things but not often beetles so the next thought is a kestrel as they do eat beetles alot. But we won't really now what is using the tower as a night time roosting spot until we get a good look at it but it is still a nice thought that the wildlife are finding it useful.
While whizzing round the path I could see that the colours are changing on a daily basis and the the birches had been letting loose their seeds. Birch seeds are small with big wings so that they can travel a long way. This is why birch trees are so good at colonising new areas. These seeds are usually spread around by the wind but I noticed another method of seed dispersal. There steadily making its way across the path was one of the great big black slugs that patrol the Moss. My daughter always used to call them dog poo slugs due to the fact that they were often found in close proximity to the aforementioned substance, plus the big ones are nearly that size. Anyway there stuck to this slugs back was a birch seed being gently carried off to another part of the moss to maybe be another birch tree. I wonder how it will get on....and the slug.