I'm Watching You!!

.....by golly I'm watching you!!!

I have a cat problem. I've had this problem daily, sometimes twice daily, for the last 10 months - enough is enough! 

Our section is fully fenced, it can't be a dog problem. 
 
There are seven cats, that I'm aware of, who parade along our fenceline, amble through the garden or fly through on a mission. They are devious and wait until no-one is watching, wait until no-one is home or until the curtains are pulled and then do their business on my lawn! Talk about sneaky and cheeky!! No they don't dig in the garden as it seems they don't like the mulch and yet its good enough for the birds to flick around, perhaps they're not quite so fussy. 
 
There's no designated spot, just anywhere that takes their fancy on my lawn, front, back, to the north, east or west - it lies there until I come along and tidy it up. Sometimes they try half-heartily to cover it up by ripping up the grass but it doesn't work very well.
 
I hate this job, I rant and rave to anyone who wants to listen or even just to myself!
 
It can't be spot treated because the area is big.....what do I do?

I realise it's unusual behaviour for a cat.
 
I feel like I'm a prisoner in my own garden, having to watch where I walk just in case they've left it behind. It's embarrassing if anyone visits as you can be sure after I've done a scout around, the cat/s sneak in before the visitor arrives.
 
I would love to solve this problem, I would love to amble my garden without having to watch my step, I would love to not be watching out the windows trying to spot the cat/s, I would love to think it will just go away but it hasn't as yet - perhaps keeping the hose handy is an answer, I don't know..........!
 
And I love my low maintenance garden especially now when life is so busy, it's my haven. I don't really want to change the mulch and to honest I'm not sure it would change the behaviour of the cat/s..........  
 
Any ideas - other than getting our own cat.........
 
And don't get me started on the loss of bird life - that's another story!

Feeling a bit disgruntled today, not a good Thursday!

But do check out mum's blip, it's a special one from her garden and she's a bit happier than I :))