My cat just swallowed a bird whole?!?

I saw this little birdie on my porch and I went to go get my camera and take a picture and the my cat came out of no where and took the bird in his mouth and I went to try and get him to spit it out but he swallowed it whole and now he looks a bit sick?? Is there something I can do so he won't get sick... My mom said she will not go to the vet... Or do you think he'll b fine?