Perhaps cats and dogs are preventing worse deaths through starvation. Others might wonder whether some other predator would eat the prey if the cats and dogs did not.
However, the evidence suggests that this is not the case. Cats have contributed to 14% of modern mammal, reptile, and bird extinctions. While dogs are understudied, they likely also contribute to extinctions.
This doesn’t follow. The worse-death-through-starvation argument is that for animals, the environment is Malthusian, so any animals born in excess of the area’s carrying capacity will starve. But the environment is shared between species; if one bird gets killed, that frees up food for one bird of similar size, but not necessarily one of the same species. So predation by household pets can be mostly offset by preventing counterfactual starvation, even if they drove a prey species to extinction—provided the counterfactual starvation deaths prevented are of a competing species.
This doesn’t follow. The worse-death-through-starvation argument is that for animals, the environment is Malthusian, so any animals born in excess of the area’s carrying capacity will starve. But the environment is shared between species; if one bird gets killed, that frees up food for one bird of similar size, but not necessarily one of the same species. So predation by household pets can be mostly offset by preventing counterfactual starvation, even if they drove a prey species to extinction—provided the counterfactual starvation deaths prevented are of a competing species.