The number one rule of nature is "survival of the fit". (adaptability). Humans try and sometimes succeed in thwarting this rule of nature. We usually do it because we believe it is the humane or right thing to do. But how do we choose when, what and how?
Man has influence, but can not (we have tried over and over) best nature. As has been said by someone else earlier in this thread, everything comes to an end. It just comes down to when, where, why and how.
Sometimes it is better to let nature control itself, than for man to take the wheel. Species come and go. It is the way of earth. Sometimes it is a good thing that a species "goes" (maybe man made killer bees, or the Black Widow spider). Can you imagine if North America had T-Rex roaming the Midwest states?
Often you see documentaries on TV about a camera man following a motherless baby elephant or baby rhino, which is starving, around for weeks, until it dies of starvation or is killed by predators. I often watch and wonder why the camera man and his crew do not help the poor thing.
Their explanation is that because it is nature, it is the unwritten law of naturalist and those involved in this type of work that humans should not get involved if humans did not have a hand in what caused the problem in the first place. (ie: if poachers killed the mother elephant, then it would be alright and actually incumbent upon humans to help the baby. But if lions or disease killed the mother elephant, then humans should not get involved in saving the baby.)
I understand this "unwritten law" and guess it is probably a decent way of dealing with these types of situations. Although I can not "do nothing" myself, when a needing living thing comes before me. I know that most who frequent this web site feel the same way.
It is a quandry for sure. A personal decision each and every time.
Would you save a feral pigeon from the clutches of a Cooper's Hawk, if they were struggling in the grass, in a park, as you just happened to be walking by? Would you save a kitten being attacked by a Red Tail Hawk in a similar situation? Would you use a live minnow in an attempt to catch a bigger fish for sport or food? Would you save a grasshopper that was in the clutches of a Praying Mantis in your garden?
Hawks and Praying Mantis need to eat also.
Don't even get me started on Bull Fighting, Hunting and Trapping!
I don't know the answer to these types of questions, but I know what I can live with within myself. My own little world.
One of my personal interests is the "Thylacine" ( also known as the Tasmanian Tiger), which is allegedly extinct. Below is a link to a video of them while still alive. Fantastic creature. Some anecdotal evidence suggests that there may be some still around, but most likely not. When it went extinct, the earth did not change. Nature did not go topsy turvy. The circle of life was not greatly interupted. What happened is we simply feel bad about it. But life and earth goes on. With or without Tasmanian Tigers and mankind.
P.S. You will like this animal in the video. Facinating. "Possibly" still in existence (let's hope).
http://www.youtube.com/watch?v=6vqCCI1ZF7o