The author has had half-dead lizards dropped in his lap or at his feet, and countless cat owners get presented with similar “gifts”—dead or half-dead birds, mice, toads and so on. It horrifies some people but delights others.
Give a cat credit for good intentions: an animal who is mostly selfish is sharing the spoils of the hunt with you. There may be some pride involved, too, which you can see on the face of a cat marching home with the prey held high in his mouth. A combination of “Look what I did!” and “Here, master, I brought you something!” Isn’t it kind of silly to get angry when this happens?