i have quite a young cat, who would catch a bird if he could, but i feel so sorry for the poor birds in this weather. if i bought a fat ball and hung it onto an overhanging bush it would be ok wouldnt it? cat would have to leap into mid air off a very narrow fence to catch a bird from this vantage point, so i think it unlikely he could catch anything from there.
Only thing to be wary of is little bits of fat tend to fall to the floor then the birds go down to peck them up. Maybe you could put a tray underneath?
You're never going to stop a determined cat mandimoo, the chances are he'll catch birds in other people's gardens if he can't catch them in yours so you may as well feed them. Please put fatballs in proper hangers, don't leave them in those net bags, and try to have some water in a shallow dish or tray available.
Be aware that the squirrels (if you have them) might steal your fatballs if they can get them out of the hangers - and they can!
It can be quite difficult to feed birds if you own a cat like we do & when the squirrels are about too!
We gave up with the bird table years ago, as the squirrels & some local cats had a field day with it!
We put wild bird seed/nuts/fat balls in proper containers - well worth paying a bit exra for (& as Robi says, not in net bags which can harm the birds). We also put dried mealworm out for them in a flat dish on the patio, so we can watch & shoo away any preditors whislt they're having a munch!
We obviously keep our cat Milly in when we put food out on the patio & she just has to sit watching the birds from indoors like we do!
Don't start to feed the birds unless you are going to continue to do so, not just in the winter. They need food all the year round just as important to feed in the summer when they are raising their young.