I think that it may be naturally occuring. I washed off the soil to mail one of my hosta and it had an orange spot in it. But it was under the soil. So, maybe as Babka said, it just needs more soil. I have a bag of good potting soil that will work just to top them off until I can get my repotting done. The thing I just did to deter Cleo was to put 4 feet under each of the pots. I used to use 3, but it makes them easier to knock over. Our soil is so dense, only earthworms and grubs can navigate it. We have no soil borne animals. I'm surprised that she hasn't caught a squirrel yet. She spends a lot of time stalking them. We'll see what it takes to save the hosta from damage. bk

We have three squirrel houses in 3 different trees and the only critters we've seen giving the squirrels any grief are raccoons. The first one I built is designed differently than yours, with a roof that overhangs the front. One time a raccoon hung over the front and managed to reach in and get a hold of one, although he didn't get it. I promptly put a little rail on top to block them. We've had Cooper's hawks come through and stalk them but never seen one try and get in one of the houses. No foxes around here, so I can't say. It's not as easy for a larger predatory bird to get at them in the box. Some boxes have ledges installed underneath the hole on the inside to keep other predators from reaching them. 6-7 feet is kind of low. The general recommendation is at least 15 feet although some say 10 is enough. Mine are about 15, 20 and 25 feet up. The one has been up for 8 years and I put two more made from tires up last year. What can I say? I found a plan, was curious and had an old tire. I almost laughed when I saw them moving in last fall. ("SOB! They work!") When you hang them, give them some kind of nesting material to get them started. I put dry crushed or mulched leaves in ours, about 1/3 filled. One caveat about your box. Even being one inch thick, pine will rot over time, especially the floor. Even though it has a hole for drainage, water will collect in there from time to time. I made mine of cedar and it's held up well, but I can see I'll have to replace the floor or build a new one before long. I got the idea for the tire ones from a guy who sells them online.(Not myself) They hang from hooks and he sells them with a rope and attachment to fling it over a limb. I also found a plan for a different style house made from a tire. They seemed to like them just fine.

LOL!! I was just this afternoon repotting a container of flat leaved parsley that had gone to seed. Dumping the old plants and soil out, I discovered a big ole horse chestnut planted - by squirrels - in the container!! Usually I find these in spring as I groom and fertilize my collection of container plantings by the telltale sprouting of a baby horse chestnut seedling. But for whatever reason this one did not germinate. I have plenty of garden they could bury/hide these dang nuts in but they seem to prefer my containers. And apparently what we have here are mostly gray squirrels, which have very poor memories and forget where as much as 75% of their buried treasure is located. Let me know if anyone wants a baby horse chestnut :-) I'm sure I'll have plenty to share next spring !!

I have a concrete dining table which was not sealed. It looks like your driveway. Hope this article helps in explaining why concrete can change colors. https://randmconcrete.com/why-is-my-concrete-discoloring/