The starting point
As we've seen, the vast majority of animals born in the wild experience mostly suffering and die very young. For many of them, it seems life wasn't worth living.
The objection
"We're not in a position to judge whether an animal's life is worth living. A life that looks bad from the outside might be good for the one living it."
It's hard in some cases
The author agrees that there are hard cases, where we can't tell whether a life is worth living.
But most cases are extreme
Almost all the cases the proposal deals with are extreme situations: a baby animal that is born and starves within a few days, a tadpole eaten right after hatching, an animal slowly dying of a disease. In cases like these, it's really hard to imagine that life was good for the one who lived it.
"But life could get better"
Someone might say: "A life might have been bad so far but get better later." That's true. But it's not an objection to the proposal to help. Quite the opposite: it's exactly a reason to help, so that these animals' lives get better.
In short
- Some cases are hard to judge, but most are extreme.
- Starving to death right after birth is hardly a good life.
- If a life can get better, that's one more reason to help.