I live on the third floor of an apartment building with a gorgeous view from a 44" deck. I've also had between 12 and 16 planters of various sizes over the years. It started with one planter after my brother passed away to grow a Bristle Cone Pine for him.
Over time the number of planters grew and shrank as the weather took some plants each year and I decided to add or subtract them. I've always occasionally had birds visit the planters, after which sometimes I would put bird seed in the planters.
This summer I started feeding the birds but then lessened it over time as the summer changed into fall and then winter. I part it was due to the fact the larger birds, mainly Jays, started showing up and effectively trashing the planters.
I've also had squirrels (this is an area which was a forest and is surrounded by small forests between housing and commercial areas, meaning, no shortage of squirrels and chipmunks). They love digging for nuts they buried or thought they buried, where I sometimes find peanut shells in the dirt.
But this winter a small creature started showing up in the wee hours to get into the planters and dig in the dirt. At first I thought it was a rat of some sort, and after getting a trap to find it was always empty every morning, I discovered it was a mole.
We have some moles in the area between the building I live and the one just north, but I've never seen moles, but a juvenile one found my deck and the planters, and it came almost every night to dig in the planters.
I started putting aluminum foil over the planters without plants and slowly reducing the number of planters for the mole, but it always seem to find one to dig in and spread the dirt around the deck. After the birds and squirrels, I was cleaning the deck twice a week so I could walk on it without stepping in dirt.
The deck if 6' wide by 44' long which I put outdoor carpet over the rough marine finish (hard on the bare feet), so vacuuming the deck is tedious. So after consulting garden people as the various local home improvement stores, there was three choices to deal with the mole.
A trap, either trapping or killing it, wouldn't fit the planters. Repellent, which is for yards, would ruin the carpet and wood deck. And that left the last option, poison.
This was something I didn't want, but the mole was clearly coming to the deck almost every night and there was no way to stop it without removing all the planters, something I don't want to do right now because I don't have a place to put them, and likely it would return if I brought them back.
So I checked the one planter he always dug in and cleaned to put the pellets per the instructions where it would find them, and sure enough the next morning all the signs showed the mole ate all the pellets, and I haven't seen it since.
I regret having to do this and I know many home owners consider moles a pest not worth a second thought to kill, but it just seems unfair, for the mole who was only surviving and me who had no alternative to deter it.
Somewhere though a mole died without really realizing what it had done but find some good and tasty food, which was laced with a poison. He didn't deserve it.