I can’t be careful enough and neither can you to avoid making a potential misstep that would wipe out a species that’s on the brink of extinction. Any species that is hovering so closely to a go / no-go line that it depends on the individual choices that I make (and the billions that are more or less like me in some way or another), then sayonara. It’s been nice knowing you, but I can’t be that careful. By that I mean “mankind in aggregate” can’t be that careful. (Either that, or the scarcity value of a particular organism would make it so attractive to poachers and collectors that the care taken by the rest of us is more or less moot.)
If you truly understand some of the history of life on earth, then you’ll already know that some 90% or more of the species that have ever lived here have been rendered extinct. The mean survival time for individual species seems to be around 4,000,000 years, give or take.
Aside from whatever effects man has on the planet, and yes, they are extraordinary compared to the actions of most other species (except bacteria, which made life possible for the rest of us, and termites and other insects, who contribute more to climate change than most people comprehend, and some others like that), every hundred million years or so a mass extinction event occurs to wipe out up to 75–80% of what happens to be alive at the time. Link
So take heart. Maybe our mass extinction event is coming soon (2012, anyone?) and you won’t have to worry about this any more.
I’m going to offer @lucillelucillelucille a polar bear steak, while I have some panda chops.