I tend to hold the view shared by most evolutionary biologists: that, under average circumstances, any one species on Earth may be expected to exist, for say, ten million years, before going extinct or evolving into something else.

The rate of extinction for all species on Earth is now about two hundred times accelerated from the average rate of extinction from other ages. 

If you count the world's endangered species, that number increases to 20,000 times the natural rate of extinction.  The numbers, along with a wide body of reigning theories on different endangered species, eviscerates the contention that we must deliberate whether extinctions are man-made or natural.

If you look at these facts alongside the more specific example of the worldwide amphibian decline, you have, in my view, a very clear indication that, statistically, very few threats of extinction in our world today would be natural, and that any natural extinctions taking place today would be statistically insignificant.

Also, conservationists and biologists aren't concerned with saving 'every species that is in trouble, for whatever reason'.  Rather, the prevailing view in the conservation movement is to view the total sum of the Earth's diversity, and to target ways to save the most diversity.

The part of our planet that matters to us is a thin band of atmosphere, populated by organisms which sustain that atmosphere.  The Chinese have this saying.  It goes something like this, "The man who removes a mountain begins by removing small stones."  Our disappearing species are the first small stones.  Science can never know the cumulative effect of our removing any one of the smallest components of our biosphere, but we have a large body of data and theories on the effects of continued species losses.

And thus, here is your fallacy: if we do not know, we must delay action in saving species.

It is rather the opposite.  We do not know the effects of the loss of one species, but we know that the cumulative effects of the loss of species and habitats provide a set of grim consequences for our own, and so it is advisable that we strengthen, not weaken, our means to protect these habitats and species.

This is what I am thinking about Lola, here at ground zero for extinction, when a tree branch breaks, and our lights catch, for just a brief moment, a whir of white.  We are now a few miles upstream, in dense wilderness, where almost anything may be wandering.

Jose whispers, "possible Crested Owl," referring to an enigmatic bird, rare for this area.  We rush forward into the dark, and soon enough, more branches break, and our lights catch the red of eyes down the cliff near the riverbank. 

We decide to scramble down the cliff, towards what appears to be night mammals.

Here, the river rushes faster, and so we jump from rock to rock approaching the source of the noise.  Mario moves fastest downstream, and follows fast moving gray fur up the bank of the river and into the trees – it's one of the local possum species, although we can't be sure.

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