Is cat litter, used for traction in an ice-slick driveway, a hazard to birds or wildlife?

Don’t use cat litter that is clay based. That would turn into a slippery injury inducing trap.

It is clay won’t harm dogs or cats. Yes it make a mess in the house when it comes in on shoes and boots.

No. It is just clay.
Oh, and a FYI, cat litter and floor dry (oil-dry) are the same thing.
You could try playground sand for your traction needs.

Clumping cat litter is made of sodium bentonite, sometimes called bentonite clay. It has the amazing property of holding water and swelling up to 10 or 20 times (maybe more) its size.
I have personally used it to seal my fish pond by sprinkling some on the water where it sinks to the bottom, falls into cracks and crevices and swells up sealing any openings.
That does not seem like a healthy choice for a bird’s digestive system.
I would not do it.
It also makes a mess of your driveway. It sticks to everything including your shoes. It will not be long before it is in your house.

There should be a label on the bag with toxicity info for that specific product.

Thanks—that’s kinda what I was afraid of. I’ll see what these products are—I think if the Oil Dry is merely clay pellets, that’s what I’ll use. Not sure about the cat litter but I’ll find out.

The bentonite is amazing stuff. I bought it in 50 pound bags for not much money, less than $10. I kept a little bit so I could experiment with it. Maybe you can do the same.
Place a little bit on a plate and add water. You might be hocked to see how big it gets. You would not want that in your stomach.

How about feeding them on cardboard trays, cut from boxes, like when stores throw out boxes from produce or cases of cans?