You forgot pigs, pheasants, ducks, snails, and every other creature that humans eat. But at least those deaths had a purpose (i.e. giving life to someone/something else), whereas the deaths of the tigers in the OP’s link had no purpose whatsoever. I’d be just as upset if someone let a herd of cattle starve to death because they were too lazy to go out and feed them. Did you mourn the death of the plants in the salad you ate the other day? After all, they were once living things.