It was really interesting to read all the comments and see the difference in opinions. I hunt with rifle and bow and both kill as long as the shot is in the correct place. I have never seen any animal shot through the heart and or lungs that did not die, if the animals doesn't die, you did not hit the vitals. Consider this, if both the rifle (adequate cal for animal) and bow (equally adequate for same size animal) hit the vitals completely broadside and in the magic triangle, the bow cuts a 1.5" plus hole through the vitals while the rifle (typical 30-06) will if the bullet fully mushrooms only be 0.6" hole. Most of the time the animal hit with the bow will go done sooner (shorter distance). However as mentioned before there are different mechanics at work in the killing power of each. The bow shot animal is normally not aware of the presence of the hunter and there are less noise. The bullet shot animal runs because of the boom and has more adrenaline in the blood and thus run further. Same happens when animals are shot over long distances (over 500m), some have at the shot jumped, but then carried on walking or feeding until they just fall over dead (due to oxygen shortage to the brain). Can you take big animals with a bow? Yes you can. If you are able to handle the poundage of the bow required to shoot that animal. We have hunted giraffe with a bow and believe me that is more demanding than a buffalo. It has a fairly thick skin, huge ribs (thicker and stronger than buffalo and hippo) and plenty of muscle. We hunted with a 80lb bow at 30" draw, capable of shooting a 780gr arrow at 253 fps, this generates 111 ft.lb kinetic energy, tipped with cut-on-impact 2 blade 1.5" diameter broadhead. This will pretty much penetrate any animal except the pachyderms (rhino, elephant, hippo). My hunting partner shot a mature giraffe bull at 50 yards, completely broad side. The arrow cleanly went through the near side rib (not breaking the rib, but cut through), penetrated the heart and logged the broad head halfway through the opposite side rib. For elephant, a 90lb bow with 1,000gr arrows at 220 fps will give the same amount of energy, but 20% increase in momentum, thus penetration. if you use the correct equipment and can handle it, and place the bullet/arrow in the correct place, you can ethically hunt any animal. PS: no arrow is designed to penetrate any bone other than ribs. DONT try head shot or shooting through the shoulder bone, it doesn't work!!!