The Biblical perspective on biodiversity doesn't directly address the
issue of endangered species. Theologians construct the argument for
protecting endangered species from various biblical and ethical
frameworks. Some are utilitarian are expressly anthropocentric–we
protect species because they might be useful for us, as sources of
medicine, useful products, or for the services they provide (like the pollination services of bees,
written about in a recent Creation Care article). But there are deeper
theological rationales for protecting species. Ron Sider was recently
cited in the Seattle Times saying, "Let's save endangered species because they come from the loving hand of the Creator." Peter Illyn has a similar take in the most recent Creation Care magazine
(Fall 08, Issue 37), where he argues that "plants and animals have an
inherent right to be fruitful and to thrive as God has commanded them."
Read the essay in full here…
Peter talks about a new threat to God's creature: climate
change. In the same issue of Creation Care, we published a beautiful
set of images of wildlife in warming world from the Irreplaceable traveling photograph exhibit. (You can see it if you download the PDF version of the magazine, which features a cover story on C.S. Lewis's environmental vision.) And Creation Care's expert conservation scientist, Kyle van Houtan, wrote a very informative explanation of extinction and its causes. One passage from his essay is particularly evocative:
putting out a fire or light, and some of its early uses appear in
Christian texts. A scientific account of animals and plants cannot by
itself describe the significance of extinction. Driving an entire group
of creatures to oblivion is more than a biological act: it is the
extinguishing of a light kindled by the One whom James refers to as
“the Father of lights” (1:17). Extinction is a theological act.
Tilling and Keeping 
Excellent post, Rusty. The general argument reminds me of a great article by Michael Bullmore on a theocentric foundation for environmentalism: that all creation, all creatures have value simply and preeminently because they’ve been created and designated as such by their Creator.
I’ll check with you sometime to see if you’d be ok with crossposting it at Not One Sparrow – Ben