If a species goes extinct and no one knows, does it matter?

In Friday's post, I questioned whether $27 million was a justified expenditure for preserving the habitat of the ivory-billed woodpecker--a species whose existence is in question and there have only been two 'possible' sightings in three years.  In the comment section an interesting philosophical debate over species extinction arose.  Since only a few people read the comments and for some reason 25% of our readers take Fridays off, I thought I would ask the question here and see what you thought:

Should all species extinctions be prevented?

Read below for some of my views and some from readers.

It seems that answering the question hinges on determining the cause of the extinction and that seems to come down to whether the extinction is human induced or 'natural.'  But that raises a broader philosophical question: 

Are humans part of the broader ecosystem, or are they just an invasive species? 

There are some who think that any human induced extinction is a bad thing and somehow interrupts the intended natural order but extinctions absent humans are somehow OK.  I guess I fall in the other camp. 

To me it is impossible to consider humans separate from the broader ecosystem.  If we accept that humans are part of the ecosytem then questions of the sort 'Does the ecosystem have inherent value separate from the values humans place on them?' become irrelevant because human services are part of the value that the ecosystem provides.  But this leads to an even stickier question:

Should we prevent extinctions regardless of their cause?

There are a number of tacts (not necessarily mutually exclusive) we can take in answering this:

1. Moralistic:  Do all species have inherent value?
2. Sustainability/Resilience:  Can the ecosystem survive in the absence of the species?
3. Precautionary:  In the face of uncertain ecological outcomes, should we preserve species at all costs?
4. Economic:  Do the expected benefits outweigh the costs of preservation?

I'm sure there are many other questions we could ask and I'm not sure we will ever know the right answer, but I do know that among the options I've listed above, only options 2 and 4 offer questions that can be investigated with scientific methods--and I'll take that over philosophical debate any day. Then again, that's probably a philosophical question we can debate.  My head hurts.