It is a behavioral characteristic of domestic cats to catch things and bring them to their owner's home and leave them on the door step. Unless that is if you have a cat door. Then, they sometimes, unfortunately bring it all the way to your feet.
Visa is the name of my small calico female cat. I adopted her because she showed up in my yard and hung around me as I worked outside like she was a puppy or something. She liked bugs, which was OK with me. But the day she showed up with a large bumble bee in her mouth I thought maybe I should feed her some real cat food. That of course sealed my fate. I became her servant and Lord at the same time (read that as Mother and Kitten). Cats are like that. She is named Visa because she is "Everywhere You Want To Be." She is about 7 years old now and is still the most active hunter of all of my cats.
One trick she has is to lay in wait on top of a six foot fence that separates our back yard from our back-back yard which is my domain. She waits there, just where the opening between the two yards is and when a bird flies low through the opening she comes down on it from above. 99% of the time she misses. Even when she succeeds she usually lands so hard that the bird escapes her. But on the occasion of all of the physics working right, she does succeed.
If I am in the yard then she brings it to me. I distract her and the bird goes free. But when she catches one, and then brings it into the house things get dicier. So today she does just that.
I see her trotting towards me in my chair with a sparrow in her mouth. Now the bird is not dead. It isn't even crippled. Scared to death, yes, but alive and flyable. In these circumstances my normal distracting Visa so the bird can escape is not a viable option. Especially when my wife sitting next to me is screaming something about, "Don't you dare let her let that bird go inside my house!" I really hate it when she says stuff like that.
Of course then the bird flies off and Visa follows. The word is is melee! Here I should say that the other two cats were not around during this episode. If they had been, they too would have been in pursuit. It is the prey-flight/carnivore-attack syndrome you know. Wife screams at the cat and me and in general.
Then of course she brings it over to me again and Wife says. Take it away from her. I tried, but of course she grabs it away first and sits there with it in her mouth.
So I go back to the camera and take another picture, at which my wife gets up and leaves in disgust.