Often, when species creep toward and then fall off the edge of existence, it is because of either a catastrophic event (which might include attack by enemies) or because their place of being has been disturbed or destroyed. Every creature has some environmental elements which are essential for survival. Sometimes it is possible for them to adapt to new conditions or move to an area with similar ones. Sometimes that is not possible.
A friend told me recently of walking through the space in which she found herself, imagining it without human contact, or after human contact. Having witnessed how the earth reclaims all that falls upon it, trees growing up through abandoned farmsteads, the jungle quickly engulfing villages, it is easy, and a little eerie, to paint pictures in the mind. Time + Weather = slow but sure decay/deconstruction/decomposition. Given a chance, earth, air, water, wind, fire, and the shifting of stones, wear the edges off of everything. Colors become muted tones that return to those found in nature, like hybrid Iris which, if not divided, return to small, pale yellow or lavender blooms and then no blooms at all.
However, all that is broken is neither lost nor useless. Sometimes beauty is multiplied through transformation. The trick is letting the original form either pass from the mind's eye or remain as shadow only, enhancing through absence.
In ancient Japan, broken pottery was repaired with gold and thereby made more precious than the original, light shining along the break lines. The process takes time and timing, but if successful, something once dear can be reborn into beauty. Some say it may be too late for us, as a species. The balance may be too far out of plumb, but maybe not. One never knows; things happen that defy explanation. I am not saying the M word. I'm simply saying, things happen.