John makes a good point.  And I am a greenie!
What is more environmentally friendly...a pair of plastic crocs, made from irreplaceable and finite petrochemicals, brought out of the ground in a country where they steadfastly refuse environmental regulation because it cuts into oil revenue.  
Or a pair of leather boots/shoes, made of cowhide grown on a cow that has been fed corn raised in huge monoculture agri-wasteland, fertilized with tons of artificial nutrient (again, petrochemical based), sprayed with pesticides (whoa, petrochemical based again) that contaminates water sources and have an unintended by-kill of good insects estimated 8-10x greater than the "bad" insects? 
Needless to say, there is no perfect answer.  As for me, I have found several really nice bullsnakes in the last few years.  I immediately caught them up, looked 'em over for flaws in the hides...and then turned them loose because I cannot make myself kill one of these sweethearts.  I'll pick up a roadkill though!