Are humans the only species that kills other species to extiction?

If not, who would be the runner up?

No. Many species of birds on islands have been driven to extinction by black or Norway rats or other predators introduced by humans. If you are talking about recent extinctions, I would probably give the prize to the black rat. However, many earlier extinctions were probably caused by introductions of the Polynesian rat.

The Brown Tree Snake wiped out most of the native birds of Guam after it arrived there.

Millions of species went extinct long before there were any humans around. Something killed them, and chances are most of them got eaten.

The cyanobacteria were many species, but they were also responsible for an unfathomably huge number of extinctions. I suspect that if you took the number of species wiped out by the oxygenation of the atmosphere and divided it by the number of cyanobacteria species alive at the time, that it would dwarf anything humans have done.

I don’t think invasive species introduced by humans should count.

Why not?

What’s the point of your question? To demonstrate that humans are somehow unique in being able to drive prey species to extinction? We’re not.

It’s just that most species that can drive other species to extinction have already done so. It’s tough to catch one in the act, so to speak.

There is the urban legend of the Stephens Island Wren, The entire species allegedly wiped out the lighthouse keeper’s cat, Tiddles.

Ditto.

Other species may have driven others to extinction, but not in a concerted, deliberate manner. Rather, they were interested in their own needs, and the other species lost.

Sounds pretty similar to humans. I doubt any human ever said, “There’s the last one! Let’s kill it and it’ll be extinct!”. See http://en.wikipedia.org/wiki/Dodo#Extinction, for example.

The extinction of the Great Auk was pretty close to that - it wasn’t quite “let’s make this thing extinct!”, it was more like “Hey, I thought those were extinct! - this could be our last chance to kill one!”

Runner up? I should think we would be one of the runners up.

I think man is the only animal that is capable of recognizing what extinction is, and has decided to do something about it in some cases.

Urban legend?

While we can’t know for sure that the cat “Tibbles” (not Tiddles) was the individual cat that killed the last wren, there is no doubt that the species was exterminated by cats. There is also no doubt that Tibbles was one of the cats killing wrens at the time the wrens vanished.

So it is entirely plausible that Tibbles did indeed wipe out the species. Saying that it is an urban legend is a bit of a stretch. Unproven certainly, but quite plausible and with some factual basis.

Why?

What about natural invasive species? Do they count? When North and South America collided large numbers of species were exterminated by invasive species. Do you think we shouldn’t count those either?

Fossils of the Stephen’s Island Wren have been found on the main islands of New Zealand. It was probably wiped out on the main islands by the introduction of Polynesian rats. The extinction of the last surviving population on Stephen was just the coup de grace.

As Blake says, the only “urban legend” aspect of the story is that the species was wiped out by a single cat. There is little doubt that the bird was wiped out by feral cats within a year of of their introduction to the island after the lighthouse was constructed.