Yes, welcome to Pet Talk! I love it here and hope you will come to love it, too. Tell us more about your cat(s) please!

I would discourage your cat from eating birds, although if they are healthy there should be no health impact for the cat. The ecological impact is more what concerns me...

I've been trying to fight back a flippant response ever since I first read your post (so sorry all bird lovers here) -- that the health impact to the cat was negligible so long as the bird was healthy, but the impact on the birds was incredibly bad. (some days I just can't control myself. Sorry!)