Wash the leaf several times with water. Use a hose , or soak in a tub of water. If you want seal with a clear cement sealer. Birds drink water from roadside puddles and I assume do ok. I bet there are many chemicals in those puddles. Washing the lime off the leaf wont be 100% but I beleive that the water bath will remove the majority. And the birds will appreciate the water.

Thanks so much for the response, kimmsr. I know so little about the make up of droppings that I have no idea how safe or dangerous they may be. I do know that they eat right in to the paint on my deck, so at the very least, I want to contain the damage. It's a wood deck with slots, so hosing things down just washes the mess onto my neighbor's space. I don't think that's a good idea, especially since I don't (yet) know how dangerous the poop is. I'm still thinking the best way to go is to put a bunch of potted plants underneath and let them catch the droppings and break them down as fertilizer. Unfortunately, one of the Ceanothus bushes I planted that's right underneath isn't doing very well. I'm wondering if the acid or something else in the droppings is causing problems. I'm really in need of someone with expert knowledge of the properties of bird droppings. I'm not sure if I've come to the right place or not. I'd be grateful for any help people here can provide. Thanks again!

SCG, maybe you don't have much snow cover where you are? If you do have good snow, cats shouldn't be an issue if you locate the feeder in an open area, hanging from a tree. Even the ground feeding birds will spot any cat long before it gets near and will fly up into the tree until the cat leaves. And in my experience cats don't like going out in the snow and cold anyway. Just remember to remove the feeder when the snow is gone and the weather warms.

OH dear. This is a very hot topic here. You may get some "not so nice" comments. First off I love cats, I have 4. They were brought in as strays and they have never set foot outside since (except my Ernie who likes to run out the door in the spring, I grab and bring right back in). Cats are killers of native wildlife as you have seen. There are many reports of the damage cats do to wildlife including birds. I am sure someone will send you links. There are also ways to let your cat enjoy the outdoors without puting your birds and critters at risk and I am sure you will get those links too. Please consider the safety of you cat and the safety of the critters and keep the cat inside unless you are with it. One other thought, and I am fighting with this now, your neighbors may not be any too happy with your cat in their yard. My neighbors let their cat out. First, I am a certified wildlife habitat with 5 nestboxes and 5 feeders, I have the right to not have the neighbors cat killing my critters including the frogs and toads in my pond, the cat does not belong on my property. Second the cat pees and poops in my garden. I should not have to put up with this , it's MY property. As you can tell I'm quite angry about this. Also I worry that any day I am going to see that cat dead in the road, I like the cat and would be extremly upset. Please reconsider letting your cat roam. It's not safe for the cat, your critters or birds and your neighbors will be happier. Hopefully someone can send you the link to the cat outside enclosures (I think Starlinka has one). Bells don't really work as birds do not know bells as being a threat until they have been attacked. Bless you for taking the cat in , now please keep it and the critters safe.