Stray animal issue

I've been having an issue with a few stray animals coming onto my property. We have a family dog and a few nice trees in our yard, we are renting a house so we have the backyard to use and we tie our dog out onto one of the trees in the yard to let her out to do her business, but I can't seem to leave her there for a minute without some other animal coming and disturbing our dog. I have lost count the amount of times this orange cat has come onto our property and distributed our dog (she's a big dog and we have had to by a heavy chain link to keep her tied to the tree because when this cat has come before she would break the regular dog leads with the wire in the plastic tube) this cat has also pooped multiple times in the yard which I do not appreciate as I have a toddler that runs around our backyard and we pick up after our dog but we obviously arnt watching this cat come shit every time and I don't want my son getting into that for obvious reasons. My boyfriend has called the humane society as we looked it up and the humane society is supposed to be in charge of animal control and capturing strays yet they told him that we have to catch this cat before they will come get it... Yet the website for our town and the humane society website state they are supposed to respond and capture strays. We don't have a cat so we don't have a cage for this cat, it's a stray with no collar so idk if it will hurt me if I try to touch it, and I have a young child and a big dog I have no space in my house to contain this cat if I was able to capture it and ultimately it's not my responsibility or problem. We have also had a big stray dog (assuming they are strays as we have never seen collars or tags on these animals) wandering around our backyard, this has happened twice both which we had our dog outside and my son was running around the yard, the breed was one that looked like they could be aggressive (I don't want to stereotype but it was similar to a Rottweiler or other big, stereotypical aggressive breed dog) and it had no collar and no owner anywhere around (we yelled for someone to come get their dog) so I was very nervous about the possibility of it attacking or biting, and again the dog wants to use our backyard as it's bathroom. I'm going to try calling the humane society again myself and see what they say, but honestly if they tell me I need to take care of this issue when their are two websites stating it's their responsibility to respond to these issues I'm not sure what I should do. If anyone has any advice or suggestions on what to say to the humane society to help us out that would be great. I just find it so frustrating that I can't enjoy my own backyard and can't let our own dog out in our yard without every stray animal in the neighborhood coming to bug us and use our yard as the community washroom.