I used a sting tracker on the very first black bear I killed and never after that. The bear went 15-20 yards after being spined and the string broke before the bear died. The string on the arrow effected the arrow flight and contributed to the spine shot. The other bear I have killed a string tracker wouldn't have helped because they went less than about 30 yards. The bear I have lost I doubt seriously that they could have been found with a string tracker. If a black bear is mortally wounded, he will be found within 140 yards of the shot. Heart or lungs 30 yards. Liver, 100+ yards before they lay down. I won't use them but if you do, remember that nothing will make up for a bad shot and with a good shot you shouldn't need one. I guess it really depends on the thickness of the cover and the skill of the tracker.